Coated sulfide solid electrolyte and preparation method and application thereof

文档序号：1924311 发布日期：2021-12-03 浏览：14次中文

阅读说明：本技术 一种包覆型硫化物固态电解质及其制备方法和应用 (Coated sulfide solid electrolyte and preparation method and application thereof ) 是由岳敏陈杰杨凯王倩钱超于 2021-08-27 设计创作，主要内容包括：本发明涉及固态电池领域,具体涉及一种包覆型硫化物固态电解质及其制备方法和应用。本发明提供了一种包覆型硫化物固态电解质,其为氧化物固态电解质层包覆在硫化物固态电解质颗粒表面的包覆型硫化物固态电解质。将特定的氧化物固态电解质包覆在硫化物固态电解质表面得到包覆型硫化物固态电解质,其氧化物固态电解质层具有相对较高的离子电导率,具有高的化学稳定性,对空气中的水分不敏感,与高压正极材料配混时的电化学稳定好,抑制了空间电荷的形成,从而成功地解决了硫化物固态电解质对水稳定性差和硫化物固态电解质与正极材料混合使用时电化学窗口不匹配的问题。(The invention relates to the field of solid-state batteries, in particular to a coated sulfide solid-state electrolyte and a preparation method and application thereof. The invention provides a coated sulfide solid electrolyte, which is a coated sulfide solid electrolyte with an oxide solid electrolyte layer coated on the surface of sulfide solid electrolyte particles. The surface of the sulfide solid electrolyte is coated with a specific oxide solid electrolyte to obtain the coated sulfide solid electrolyte, and an oxide solid electrolyte layer of the coated sulfide solid electrolyte has relatively high ionic conductivity, high chemical stability, insensitivity to moisture in air, good electrochemical stability when being mixed with a high-voltage positive electrode material and inhibition of the formation of space charge, so that the problems of poor stability of the sulfide solid electrolyte to water and unmatched electrochemical windows when the sulfide solid electrolyte is mixed with the positive electrode material for use are successfully solved.)

1. A coated sulfide solid electrolyte is characterized in that an oxide solid electrolyte layer is coated on the surface of sulfide solid electrolyte particles;

the oxide solid electrolyte is LiNb_xTa_1-xO₃(0.15. ltoreq. x. ltoreq.0.85) type, LiPON type, and NASICON type.

2. The coated sulfide solid electrolyte of claim 1, wherein the LiPON type is Li_3.3PO_3.9N_0.17Further preferably, the NASICON type is Li_1.4Al_0.4Ti_1.6(PO₄)₃。

3. The coated sulfide solid electrolyte according to claim 1 or 2, wherein the sulfide solid electrolyte is (1+ x) Li₂S·xP₂S₅(x is more than 0 and less than 1) type, Li_6-yPS_5-yX_1+y(X ═ Cl, Br, I, 0. ltoreq. y.ltoreq.0.6) type and Li_11- _zM_2-zP_1+zS₁₂(M ═ Ge, Sn, Si, 0.5. ltoreq. z.ltoreq.1.5) type.

4. The coated sulfide solid electrolyte according to any one of claims 1 to 3, wherein D of the sulfide solid electrolyte particles_N50 particle diameter of 0.50 to 30.00. mu.m, preferably, D of the sulfide solid electrolyte particle_N50 particle diameter of 0.50-3.00 mu m, D of the coated sulfide solid electrolyte_NThe 50 particle diameter is 0.53-3.08 μm.

5. The coated sulfide solid electrolyte according to any one of claims 1 to 4, wherein the thickness of the oxide solid electrolyte layer is 8.00 to 100.00nm, preferably 8.50 to 99.60 nm.

6. The coated sulfide solid state electrolyte according to any one of claims 1 to 5, wherein the coated sulfide solid state electrolyte has an initial ionic conductivity of 0.35 to 9.2mS/cm, preferably the sulfide solid state electrolyte has an initial ionic conductivity of 0.68 to 10.8 mS/cm.

7. The method for producing the coated sulfide solid electrolyte according to any one of claims 1 to 6, comprising the steps of:

(1) carrying out ball milling on a sulfide solid electrolyte raw material, and sequentially carrying out tabletting, sintering, grinding and screening to obtain sulfide solid electrolyte particles, wherein the ball milling and sintering are carried out under an inert condition;

(2) and preparing an oxide solid electrolyte layer on the surface of the sulfide solid electrolyte particle by adopting a wet coating method or a physical vapor deposition method to obtain the coated sulfide solid electrolyte.

8. The preparation method according to claim 7, wherein the pressure of the tablet in step (1) is 100-1000MPa, preferably the sintering temperature is 350-600 ℃, and further preferably the sintering time is 2-15 h.

9. The method according to claim 7 or 8, wherein the wet coating method of step (2) comprises the steps of:

(A) dissolving an oxide solid electrolyte raw material containing lithium, tantalum ethoxide and niobium ethoxide in alcohol to obtain a precursor solution under an inert atmosphere, wherein the alcohol is preferably absolute ethyl alcohol;

(B) spraying the precursor solution prepared in the step (A) on the surfaces of the sulfide solid electrolyte particles, pre-sintering in an inert atmosphere, and sintering in a pure oxygen atmosphere to obtain the coated sulfide solid electrolyte.

10. The method according to claim 9, wherein the spraying rate in step (B) is 5-15g/min, preferably the spraying time is 1-5min, further preferably the sintering temperature is 200-600 ℃, and further preferably the sintering time is 1-3 h.

11. The method according to claim 7 or 8, wherein the physical vapor deposition method is one of a magnetron sputtering method, an atomic layer deposition method, and a vacuum evaporation method, preferably a magnetron sputtering method.

12. The method of claim 11, wherein the magnetron sputtering method comprises the steps of:

(a) grinding and tabletting the oxide solid electrolyte and the binder to prepare a target material;

(b) opening the magnetron sputtering equipment, installing the target material and the substrate, and vacuumizing the cavity to 1.0 multiplied by 10^-4-10.0×10^-4Pa, regulating the air pressure and the sputtering power, and introducing inert gas for sputtering.

13. The method as claimed in claim 12, wherein the sputtering power in step (b) is 50-400W, preferably 100-300W; preferably, the sputtering time is 100-; sputtering gas pressure of 2.5X 10^-1-9.0×10^-1Pa。

14. Use of the coated sulfide solid-state electrolyte according to any one of claims 1 to 6 or the coated sulfide solid-state electrolyte produced by the production method according to any one of claims 7 to 13 in a solid-state battery.

15. A solid-state battery comprising a positive electrode, a solid-state electrolyte, and a negative electrode, wherein at least one of the positive electrode, the solid-state electrolyte, and the negative electrode comprises the encapsulated sulfide solid-state electrolyte according to any one of claims 1 to 6 or the encapsulated sulfide solid-state electrolyte produced by the production method according to any one of claims 7 to 13.

Technical Field

The invention relates to the field of solid-state batteries, in particular to a coated sulfide solid-state electrolyte and a preparation method and application thereof.

Background

Along with the rapid development of portable mobile electronic equipment, the popularization and application of new energy automobiles and the construction of smart power grids, people have increasingly strong demands on efficient energy storage equipment. The lithium ion battery has become the main force in the existing energy storage equipment by virtue of the advantages of high energy density, no memory effect, high working voltage and long cycle life. At present, ester or ether organic liquid electrolyte is used in commercial lithium ion batteries, and is volatile, easy to decompose, easy to leak and the like in the use process, so that the service life of the batteries is seriously influenced, and meanwhile, the organic electrolyte is easy to generate side reaction with electrode materials in the electrochemical circulation process, so that flatulence is generated, and potential safety hazards such as ignition and explosion exist. In addition, in order to obtain high energy density, metal lithium has application prospects as a lithium ion battery negative electrode material, but during charging and discharging, the metal lithium is easy to grow lithium dendrites in a liquid electrolyte, and the lithium dendrites can penetrate a separator and cause short circuit, ignition and even explosion.

Compared with liquid electrolyte, the solid electrolyte has the advantages of no exertion, nonflammability, no corrosion, high mechanical strength and the like, avoids the phenomena of electrolyte leakage, electrode short circuit and the like in the traditional liquid lithium ion battery, reduces the sensitivity of the battery pack to temperature, can effectively prevent the growth of lithium dendrites due to the high mechanical strength of the solid electrolyte, and has extremely high safety in the use process.

At present, the solid electrolyte mainly comprises oxide, sulfide and polymer solid electrolytes, wherein the oxide solid electrolyte is insensitive to the environment, has excellent water resistance and oxidation resistance, has more stable physical and chemical properties, but has lower conductivity. The polymer solid electrolyte is formed by complexing polar macromolecules and metal salts, has good film-forming property, flexibility and high safety performance, but has lower conductivity, smaller transference number of lithium ions and poorer mechanical performance. The sulfide solid electrolyte has ion conductivity comparable to that of a liquid electrolyte solution, the transference number of lithium ions is close to 1, and the electrolyte and an electrode material have good wettability, so that the sulfide solid electrolyte is suitable for high-energy-density energy storage devices and becomes one of very promising technical routes for developing all-solid batteries.

However, the sulfide solid electrolyte is particularly sensitive to water and oxygen, and has very strict requirements on the environment in the preparation and use processes, so that the large-scale application of the sulfide solid electrolyte is severely limited; in addition, sulfide reacts with a metallic lithium negative electrode when contacting with the negative electrode to generate a substance having poor ion conductivity, which is not favorable for lithium ion migration, and these problems faced by sulfide solid electrolytes greatly affect the performance of all-solid batteries.

Chinese patent CN111864256A discloses a sulfide solid electrolyte and a full solid lithium secondary battery, the sulfide solid electrolyte is a glass ceramic solid electrolyte with a glass phase and a crystalline phase which are uniformly mixed, and Li is added₂S、P₂S₅、M_xS₂O₃(M is one or more selected from Na, K, Ba and Ca, x is more than or equal to 1 and less than or equal to 2) according to the proportion, and the sulfide solid electrolyte is obtained by heat treatment at the temperature of 150-450 ℃. In the preparation process of the all-solid-state lithium secondary battery, the anode membrane is obtained by mixing and pressing an anode active material and the sulfide solid electrolyte of the invention into a layer shape. The sulfide solid electrolyte prepared by the process is still sensitive to water, and the sulfide solid electrolyte and a high-voltage positive active material are directly mixed in the positive membrane, so that more side reactions can occur in the electrochemical circulation process due to mismatching of electrochemical windows; secondly, the preparation of the positive electrode membrane needs to be carried out under an inert atmosphere, which greatly increases the preparation cost and is not beneficial to industrial mass production.

Chinese patent CN112203975A discloses a sulfide solid electrolyte and a battery, and the present invention relates to a solid electrolyte useful as a lithium secondary battery or the like, which has a characteristic of suppressing generation of hydrogen sulfide gas even when exposed to moisture in the atmosphere, contains lithium element, phosphorus element, sulfur element and halogen, and has a crystal phase or compound of a germanite type structure. The sulfide solid electrolyte prepared by the process can not effectively isolate moisture, is still sensitive to moisture in the using and storing processes, and still generates a large amount of hydrogen sulfide gas in an environment with lower humidity. When a battery is assembled by using the sulfide solid electrolyte, the problem of an interface between the battery and a high-voltage positive electrode material cannot be effectively inhibited.

Chinese patent CN111740152A discloses a high-performance sulfide solid electrolyte and a preparation method thereof, the invention provides a high-performance sulfide solid electrolyte with high ionic conductivity and low electronic conductivity, wherein, two or three raw materials are mixed according to a certain molar ratio, ball milling and sintering are carried out, and the two processes are carried out in an inert atmosphere to obtain Li with a general formula of (100-x)₂P·xP₂S₅yM sulfide solid electrolyte, wherein M is zinc oxide, phosphorus pentoxide, lithium fluoride, lithium chloride. The chemical stability of the solid electrolyte is improved by doping oxygen element, fluorine element or chlorine element into the sulfide solid electrolyte. However, the sulfide solid electrolyte obtained by the process still has high requirements on the atmosphere during use and storage, the oxygen content is not more than 0.1ppm, the water content is not more than 0.1ppm, and the harsh low dew point environment makes the sulfide solid electrolyte difficult to industrialize.

Chinese patent CN111908437A discloses a preparation method of sulfide solid electrolyte, which is prepared by mixing Li₂S、P₂S₅And the lithium salt of the halide are mixed, ground and sieved according to the stoichiometric ratio to obtain a precursor which is uniformly mixed, then the precursor is placed in a ceramic vibration tank in microwave equipment to be vibrated and turned over, and is subjected to microwave sintering at the temperature of 150 ℃ and 400 ℃ for 10min-1h, and the cooled precursor is cooled to obtain the Geranite type solid electrolyte containing elements of lithium, phosphorus, sulfur and halogen. The sulfide solid electrolyte of the invention has higher ionsThe conductivity, however, is extremely unstable in air, limiting the practical application of the solid electrolyte.

Chinese patent CN109509910A discloses a composite solid electrolyte and a method for preparing the same, which improves the interface problem between a sulfide solid electrolyte and an electrode material by compounding an amorphous oxide solid electrolyte on the surface of the sulfide solid electrolyte. The composite solid electrolyte provided by the invention does not solve the problem of poor stability of sulfide solid electrolyte to humidity and oxygen, and during assembled battery testing, the problem of voltage mismatching of a positive electrode material and the sulfide solid electrolyte cannot be avoided in the positive electrode sheet preparation process, so that the cycle stability is seriously influenced.

Disclosure of Invention

The problems to be solved by the invention are as follows: the stability of the sulfide solid electrolyte to water is improved, and the matching degree of an electrochemical window when the sulfide solid electrolyte and a positive electrode material are mixed for use is improved.

In view of the above problems, an object of the present invention is to provide a coated sulfide solid electrolyte with high stability, which can effectively improve the stability of the sulfide solid electrolyte to water and the electrochemical stability when the coated sulfide solid electrolyte is mixed with positive and negative electrode materials for use; the second purpose of the invention is to provide a preparation method of the coated sulfide solid electrolyte; the invention also aims to provide the application of the coated sulfide solid electrolyte in a solid battery; it is a fourth object of the present invention to provide a solid-state battery containing the above-described encapsulated sulfide solid-state electrolyte.

In order to solve the problems, the technical scheme of the invention is as follows:

a coated sulfide solid electrolyte is a coated sulfide solid electrolyte in which an oxide solid electrolyte layer is coated on the surface of sulfide solid electrolyte particles;

the oxide solid electrolyte is LiNb_xTa_1-xO₃(0.15. ltoreq. x. ltoreq.0.85) type, LiPON type, and NASICON type.

Preferably, the LiPON type is Li_3.3PO_3.9N_0.17Further preferably, the NASICON type is Li_1.4Al_0.4Ti_1.6(PO₄)₃。

Preferably, the sulfide solid electrolyte is (1+ x) Li₂S·xP₂S₅(x is more than 0 and less than 1) type, Li_6-yPS_5-yX_1+y(X ═ Cl, Br, I, 0. ltoreq. y.ltoreq.0.6) type and Li_11-zM_2-zP_1+zS₁₂(M ═ Ge, Sn, Si, 0.5. ltoreq. z.ltoreq.1.5) type.

Preferably, D of the sulfide solid electrolyte particle_NThe 50 particle diameter is 0.50-30.00 μm, preferably 0.50-3.00 μm; preferably, D of the coated sulfide solid electrolyte_NThe 50 particle diameter is 0.53-3.08 μm.

Preferably, the thickness of the oxide solid electrolyte layer is 8.00 to 100.00nm, preferably 8.50 to 99.60 nm.

Preferably, the coated sulfide solid state electrolyte has an initial ionic conductivity of 0.35 to 9.2mS/cm, and preferably, the sulfide solid state electrolyte has an initial ionic conductivity of 0.68 to 10.8 mS/cm.

Preferably, the method for producing the coated sulfide solid electrolyte includes the steps of:

Preferably, in the preparation method, the pressure of the pressed sheet in the step (1) is 100-1000MPa, the sintering temperature is 350-600 ℃, and the sintering time is further preferably 2-15 h.

Preferably, in the above preparation method, the wet coating method in step (2) includes the following steps:

Preferably, in the above preparation method, the spraying rate in step (B) is 5-15g/min, preferably, the spraying time is 1-5min, further preferably, the sintering temperature is 200-600 ℃, and further preferably, the sintering time is 1-3 h.

Preferably, in the above preparation method, the physical vapor deposition method is one of a magnetron sputtering method, an atomic layer deposition method and a vacuum evaporation method, and is preferably a magnetron sputtering method.

Preferably, in the above preparation method, the magnetron sputtering method includes the following steps:

(a) grinding and tabletting the oxide solid electrolyte and the binder to prepare a target material;

(b) opening the magnetron sputtering equipment, installing the target material and the substrate, and vacuumizing the cavity to 1.0 multiplied by 10^-4-10.0×10^- ⁴Pa, regulating the air pressure and the sputtering power, and introducing inert gas for sputtering.

Preferably, in the above preparation method, the sputtering power in the step (b) is 50-400W, preferably 100-300W; preferably, the sputtering time is 100-; sputtering gas pressure of 2.5X 10^-1-9.0×10^-1Pa。

The invention also provides the application of the coated sulfide solid electrolyte or the coated sulfide solid electrolyte prepared by the preparation method in a solid battery.

The invention also provides a solid-state battery which comprises a positive electrode, a solid-state electrolyte and a negative electrode, wherein at least one of the positive electrode, the solid-state electrolyte and the negative electrode comprises the coated sulfide solid-state electrolyte or the coated sulfide solid-state electrolyte prepared by the preparation method.

The invention has the beneficial effects that:

the invention obtains the coated sulfide solid electrolyte by coating the surface of the sulfide solid electrolyte with the specific oxide solid electrolyte, and the oxide solid electrolyte layer has relatively high ionic conductivity which is between 10^-4-10^- ²S/cm, high chemical stability, insensitivity to moisture in the air, good electrochemical stability when being mixed with a high-voltage anode material, and inhibition of space charge formation, thereby successfully solving the problems of poor water stability of the sulfide solid electrolyte and unmatched electrochemical windows when the sulfide solid electrolyte is mixed with the anode material for use. In the process of preparing the coated sulfide solid electrolyte, the technological conditions such as sintering temperature and the like are strictly controlled, the chemical stability of the coated sulfide solid electrolyte is obviously improved, and the industrial large-scale production becomes possible. On the other hand, the coated sulfide solid electrolyte is more adaptive to a high-voltage positive electrode material, and the prepared solid battery has more excellent electrochemical performance and higher safety performance.

Drawings

FIG. 1 is a schematic view of a coated sulfide solid electrolyte according to an embodiment of the present invention;

fig. 2 is a schematic diagram of a solid-state battery according to an embodiment of the present invention.

The designations in the figures illustrate the following: a-sulfide solid electrolyte, B-cladding sulfide solid electrolyte, C-anode, D-cathode and E-solid electrolyte.

Detailed Description

In order to make the purpose, technical scheme and technical effect of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention is clearly and completely described. The embodiments described below are some, but not all embodiments of the invention. All other embodiments obtained by a person of ordinary skill in the art without any inventive step in connection with the embodiments of the present invention shall fall within the scope of protection of the present invention.

In the description of the present invention, where numerical ranges are used, they include both endpoints, the units being common. For example, a particle size of the sulfide solid electrolyte of 0.5 to 30.0 μm means that the particle size of the solid electrolyte is 0.5 μm or more and 30.0 μm or less.

In the description of the present invention, "at least one" means one kind or plural kinds, "plural kinds" means two or more kinds. For example, "one or more of a, b, or c," or "at least one of a, b, and c," may each represent: a. b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, wherein a, b, and c can be single or multiple respectively.

In the description of the present invention, "D_NThe 50 particle size "refers to the particle size corresponding to the percentage of the cumulative particle size distribution of the sample at 50%.

It should be understood that the mass of the related components mentioned in the embodiments of the present invention may not only refer to the specific content of each component, but also represent the proportional relationship of the mass between each component, and therefore, it is within the scope of the disclosure that the content of the related components is scaled up or down according to the embodiments of the present invention. Specifically, the weight described in the embodiments of the present invention may be a unit of mass known in the chemical field such as μ g, mg, g, kg, etc.

In addition, unless the context clearly uses otherwise, an expression of a word in the singular is to be understood as including the plural of the word. The terms "comprises" or "comprising" are intended to specify the presence of stated features, quantities, steps, operations, elements, portions, or combinations thereof, but are not intended to preclude the presence or addition of one or more other features, quantities, steps, operations, elements, portions, or combinations thereof.

In order to better understand the above technical solution, the present invention is further described in detail below.

The invention provides a coated sulfide solid electrolyte, which is a coated sulfide solid electrolyte with an oxide solid electrolyte layer coated on the surface of sulfide solid electrolyte particles;

the oxide solid electrolyte is LiNb_xTa_1-xO₃(0.15. ltoreq. x. ltoreq.0.85), and at least one of a LiPON type and a NASICON type.

In a preferred embodiment of the present invention, the LiPON type is Li_3.3PO_3.9N_0.17Preferably, said NASICON type is Li_1.4Al_0.4Ti_1.6(PO₄)₃。

The sulfide solid electrolyte is extremely unstable in air and can generate hydrogen sulfide when meeting water, so that the use safety performance is greatly influenced; in addition, the sulfide solid electrolyte and the high-voltage positive electrode material have the problem of voltage mismatching, and space charge can be generated, so that a series of side reactions occur at the interface, the interface impedance is increased, and the electrochemical performance of the solid battery is seriously influenced. By coating LiNb on the surface of sulfide solid electrolyte_xTa_(1-x)O₃The oxide solid electrolyte layer of at least one of (x is more than or equal to 0.15 and less than or equal to 0.85) type, LiPON type and NASICON type, on one hand, the stability of the sulfide solid electrolyte to water is improved, and the generation of hydrogen sulfide gas in the storage and use processes of the sulfide solid electrolyte is obviously inhibited; on the other hand, the coating of the oxide solid electrolyte layer also plays a role in isolating the direct contact between the high-voltage positive electrode material and the sulfide solid electrolyte, and the formation of space charges between the sulfide solid electrolyte and the high-voltage positive electrode is inhibited. The selection of the coating layer takes into consideration both the stability to water and oxygen and the ionic conductivity. Wherein, LiNb_xTa_(1-x)O₃Because of the synergistic effect of the niobium element and the tantalum element, the niobium-tantalum composite material is superior to LiNbO in ion conductivity and water-oxygen stability₃And LiTaO₃。Li_3.3PO_3.9N_0.17Has higher ion conductivity and better mechanical property, stable chemical property and electrochemical property, and can be combined with LiCoO₂、LiMnO₄The positive electrode and the negative electrode are matched. Li_1.4Al_0.4Ti_1.6(PO₄)₃Not only has high ionic conductivity, but also has good chemical stability to water and oxygen, and the characteristics enable Li_1.4Al_0.4Ti_1.6(PO₄)₃Can be used as a coating layer of the sulfide solid electrolyte.

In a preferred embodiment of the present invention, in the above-described cladding-type sulfide solid-state electrolyte, the sulfide solid-state electrolyte is (1+ x) Li₂S·xP₂S₅(x is more than 0 and less than 1) type, Li_6-yPS_5-yX_1+y(X ═ Cl, Br, I, 0. ltoreq. y.ltoreq.0.6) type and Li_11-zM_2-zP_1+zS₁₂(M ═ Ge, Sn, Si, 0.5. ltoreq. z.ltoreq.1.5) type.

In a preferred embodiment of the present invention, in the above-described coated sulfide solid electrolyte, D of the sulfide solid electrolyte particles_N50 particle diameter of 0.50 to 30.00. mu.m, preferably, D of the sulfide solid electrolyte particle_N50 particle diameter of 0.50-3.00 mu m, D of the coated sulfide solid electrolyte_NThe 50 particle diameter is 0.53-3.08 μm. D of the sulfide solid electrolyte particles in order to ensure that the coated sulfide solid electrolyte is sufficiently contacted with the positive electrode active material during the preparation of the positive electrode_NThe 50 particle diameter is preferably controlled to 0.50 to 3.00. mu.m. When the coated sulfide solid electrolyte is mixed with the positive and negative electrode active materials to form slurry, the coated sulfide solid electrolyte is more prone to filling between the positive and negative electrode active material particles, which requires that the particle size of the sulfide solid electrolyte is not too large. In addition, when the particle size is too large, the contact area between particles is small, and the pores are large, resulting in large interface resistance. If the particle size is too low, the process is not favorable and the process is complicated.

In a preferred embodiment of the present invention, in the above-described coated sulfide solid electrolyte, the thickness of the oxide solid electrolyte layer is 8.00 to 100.00nm, preferably 8.50 to 99.60nm, and when the thickness of the oxide solid electrolyte layer is too thin, stability to water and oxygen is affected, and the oxide electrolyte layer is easily broken; when the thickness is too thick, the ion conductivity of the whole solid electrolyte is obviously reduced, and the cycle performance is not facilitated; in addition, because the oxide solid electrolyte has lower conductivity than the sulfide solid electrolyte, in order to avoid the coated oxide solid electrolyte layer from generating great influence on the conductivity of the sulfide solid electrolyte, the coating layer of the oxide solid electrolyte is not easy to be too thick or too thin. The excessively thick oxide solid electrolyte coating layer can cause the conductivity of the coated sulfide solid electrolyte to be obviously reduced, and the ion transmission performance is influenced; the thin coating layer of the oxide solid electrolyte can lead the stability of the sulfide solid electrolyte to water not to meet the expected target, and the safety performance of the use is influenced.

In a preferred embodiment of the present invention, in the above-described coated sulfide solid-state electrolyte, the coated sulfide solid-state electrolyte has an initial ionic conductivity of 0.35 to 9.2mS/cm, and preferably, the sulfide solid-state electrolyte has a conductivity of 0.68 to 10.8 mS/cm.

The invention also provides a preparation method of the coated sulfide solid electrolyte, which comprises the following steps:

(1) carrying out ball milling, tabletting, sintering, grinding and screening on a sulfide solid electrolyte raw material to obtain sulfide solid electrolyte particles, wherein the ball milling and sintering are carried out in an inert atmosphere;

The sulfide solid electrolyte raw material in the step (1) comprises metal sulfide, metal halide and P₂S₅Wherein the metal sulfide includes Li₂S、GeS₂、SiS₂、SnS₂And the metal halide comprises one or more of LiCl, LiBr and LiI. Specifically, the raw material components are weighed according to the stoichiometric ratio of the sulfide solid electrolyte without a certain excess.

In a preferred embodiment of the present invention, in the above preparation method, the pressure of the tablet in step (1) is 100-1000MPa, and the sintering is performed in an inert atmosphere at a temperature of 350-600 ℃ for 2-15h, wherein the temperature rise/fall rate is 2-5 ℃/min. When the pressure is too low during tabletting, the compression molding is difficult, and when the pressure is too high, the mold may be damaged. When the sintering temperature is too high and the sintering time is too long, the solid electrolyte will be melted, and the impurity phase will be increased; if the sintering temperature is too low and the sintering time is too short, the reaction is insufficient.

In a preferred embodiment of the present invention, in the above preparation method, the wet coating method in step (2) comprises the steps of:

(A) dissolving an oxide solid electrolyte raw material containing lithium, tantalum ethoxide and niobium ethoxide in alcohol under an inert atmosphere to obtain a precursor solution;

In the wet coating method, the raw materials of the oxide solid electrolyte in the step (A) are selected from metallic lithium, niobium ethoxide and tantalum ethoxide, and the metallic lithium is preferably battery-grade metallic lithium with the purity not lower than 99.6% in consideration of the purity of the synthesized product. Dissolving metal lithium in alcohol under inert atmosphere, and adding a mixture of tantalum ethoxide and niobium ethoxide after the metal lithium is completely dissolved to form a precursor solution. Using alcohol as a reaction solvent, on the one hand, considering the low cost of alcohol; on the other hand, the sulfide solid electrolyte and the alcohol can stably exist, and no side reaction occurs in the coating process. In view of toxicity and boiling point of the alcohol, anhydrous ethanol is preferred.

In a preferred embodiment of the present invention, in the wet coating method, the spraying rate in step (B) is 5-15g/min, preferably the spraying time is 1-5min, and further preferably, the spraying method further comprises drying and sieving the sulfide solid electrolyte, wherein the drying temperature is 80 ℃. The inventor finds that the spraying speed and the spraying time have a positive correlation with the thickness of the oxide solid electrolyte layer, and the thickness of the oxide solid electrolyte layer can be controlled by regulating and controlling the two parameters.

In a preferred embodiment of the present invention, in the above wet coating method, the pre-sintering in step (B) is maintained at 120 ℃ for 2 hours under an inert atmosphere, wherein the temperature rise rate is 5 ℃/min; then sintering is carried out, oxygen with the purity of 99.99 percent is introduced, the temperature is raised to 200-600 ℃, preferably 500-600 ℃, the constant temperature is kept for 1-3h, wherein the temperature raising rate is 5 ℃/min, and after sintering is finished, the cladding sulfide solid electrolyte is obtained. In the whole sintering process, the presintering is carried out in an inert atmosphere, so that a dense layer is formed on the surface of the sulfide solid electrolyte, and then the sintering is carried out in pure oxygen at an elevated temperature to remove organic groups on the surface.

In a preferred embodiment of the present invention, in the above preparation method, the physical vapor deposition method is one of a magnetron sputtering method, an atomic layer deposition method, and a vacuum evaporation method, and is preferably a magnetron sputtering method.

In a preferred embodiment of the present invention, in the above preparation method, the magnetron sputtering method includes the steps of:

(a) grinding and tabletting the oxide solid electrolyte and the binder to prepare a target material;

(b) opening the magnetron sputtering equipment, installing the target material and the substrate, and vacuumizing the cavity to 1.0 multiplied by 10^-4-4×10^-4Pa, regulating the air pressure and the sputtering power, and introducing inert gas for sputtering.

In a preferred embodiment of the present invention, in the magnetron sputtering method, the sputtering power in the step (b) is 50-400W, preferably 100-300W; the sputtering time is 100-300 min; sputtering gas pressure of 2.5X 10^-1-9.0×10^- ¹Pa。

The invention also provides the application of the coated sulfide solid electrolyte or the coated sulfide solid electrolyte prepared by the preparation method in a solid battery.

The invention also provides a solid-state battery which comprises a positive pole piece, a solid-state electrolyte and a negative pole piece, wherein at least one of the positive pole piece, the solid-state electrolyte and the negative pole piece comprises the coated sulfide solid-state electrolyte or the coated sulfide solid-state electrolyte prepared by the preparation method.

In a preferred embodiment of the present invention, in the solid-state battery, the positive electrode sheet is prepared by the following steps: weighing a conductive agent, a binder, a positive electrode active material and a coated sulfide solid electrolyte according to a certain proportion in an environment with a dew point of-30 ℃, adding the conductive agent, the binder, the positive electrode active material and the coated sulfide solid electrolyte into an organic solvent, grinding and uniformly mixing to obtain positive electrode active slurry; and uniformly coating the positive active slurry on the surface of a positive current collector to form a positive active layer, drying, rolling and cutting to obtain the positive pole piece. During the preparation process, a certain amount of coated solid electrolyte is added, so that lithium ions can be effectively conducted in the positive electrode, and meanwhile, the addition amount of the coated solid electrolyte has certain influence on the overall electrochemical performance of the solid battery.

The positive active material comprises lithium cobaltate, lithium manganate, lithium iron phosphate, ternary material and LiNi_aCo_bMn_1-a-bM_cO₂(a is more than or equal to 0.3 and less than or equal to 0.75, b is more than or equal to 0.2 and less than or equal to 0.3, c is more than or equal to 0 and less than or equal to 0.1, and M is at least one of Ti, Mg, Al, V, Cr, Zr, Ba, La, Ce and Sn). The capacity of the solid-state battery provided by the present invention is mainly contributed by the amount of the positive electrode active material, and the mass ratio of the positive electrode active material to the positive electrode active material has a significant influence on the charge/discharge capacity of the positive electrode. The electrochemical performance of the overall solid-state battery can be optimized by optimizing the amount of the positive electrode active material added.

The positive electrode current collector is selected from at least one of aluminum foil, carbon-coated aluminum foil, foamed aluminum foil and foamed nickel, and preferably, the carbon-coated aluminum foil. This is because the positive electrode is at a relatively high potential during charging and discharging, while the negative electrode is at a low potential, the current collector is easily oxidized during charging, and the surface of the carbon-coated aluminum foil has a layer of dense alumina, which can resist the oxidation, and cannot select metals such as copper foil, which are easily oxidized under high pressure.

The conductive agent is selected from at least one of SuperP, acetylene black, Ketjen black, carbon nanotube, graphene and carbon fiber. The addition of the conductive agent plays a role in enhancing the overall electron conductivity of the positive electrode, and does not serve as a source of capacity contribution. Therefore, the addition amount of the conductive agent can influence the whole capacity of the anode to a certain extent, and if the addition amount of the conductive agent is too low, the electron conductive channel is too small, which is not beneficial to large-current charge and discharge; the relative content of the positive active material is reduced by too high addition amount of the conductive agent, the battery capacity is influenced, and the optimal electrochemical performance is obtained by optimizing the mass ratio of the conductive agent in the positive active layer.

The binder is at least one selected from polyvinylidene fluoride, polytetrafluoroethylene, CMC, SBR, NBR, PVC, Polysiloxane, SEBS and SBS. If the amount of the binder added is too low, the electrode structure is hardly stabilized; too high an amount of binder added will in turn cause an increase in electrical resistance, resulting in a decrease in the relative amount of conductive agent or positive electrode active material and a decrease in the conductive properties of the resulting positive electrode.

The organic solvent is at least one selected from N-methyl pyrrolidone, dimethyl carbonate, ethyl acetate, absolute ethyl alcohol, acetone, diethyl carbonate and methyl propionate. These organic solvents do not react with the positive electrode active material, the conductive agent, the binder, and the coated sulfide solid electrolyte, and have a low vaporization temperature.

In a preferred embodiment of the present invention, in the above-described solid-state battery, the solid electrolyte sheet is prepared by: and tabletting the coated sulfide solid electrolyte under the pressure of 100MPa-1000MPa to obtain the electrolyte. Since an excessively thick solid electrolyte sheet leads to a slow lithium ion transport rate, the solid electrolyte should be made as thin as possible.

In addition, the solid-state battery negative electrode of the present invention may preferably be one of a lithium metal sheet, an indium sheet, a lithium-indium alloy, an aluminum foil, a tin foil, a lithium aluminum alloy, or a lithium silicon alloy, or a negative electrode prepared by: weighing a conductive agent, a binder, a negative electrode active material and a coated sulfide solid electrolyte according to a certain proportion in an environment with a dew point of-30 ℃, adding the conductive agent, the binder, the negative electrode active material and the coated sulfide solid electrolyte into an organic solvent, and grinding and uniformly mixing to obtain negative electrode active slurry; and uniformly coating the negative active slurry on the surface of a negative current collector to form a negative active layer, drying, rolling and cutting to obtain the negative electrode.

The negative electrode active material contains one of silicon carbon, lithium titanate or graphite, and the negative electrode current collector is selected from one of copper foil and stainless steel foil.

In a preferred embodiment of the present invention, the above-described solid-state battery is produced by the following method: and sequentially laminating the positive pole piece, the solid electrolyte piece and the negative pole, and applying pressure of 500MPa-1000MPa for cold pressing to obtain the solid battery.

In a preferred embodiment of the present invention, the solid-state battery includes, but is not limited to, one of a button cell battery, a flat cell battery, a cylindrical battery and a pouch battery.

The raw materials or reagents used in the present invention are purchased from mainstream manufacturers in the market, and those who do not indicate manufacturers or concentrations are all analytical pure grade raw materials or reagents that can be obtained conventionally, and are not particularly limited as long as they can perform the intended function. The instruments and equipment used in the present example are not particularly limited as long as they can perform the intended functions, and are commercially available from major manufacturers. The specific techniques or conditions not specified in this example were performed according to the techniques or conditions described in the literature in the art or according to the product specification.

The instrument comprises the following steps:

magnetron sputtering apparatus, available from Shenyang Jingyi research science and technology Co., Ltd, type: a high vacuum multifunctional magnetron sputtering device (101A-1B).

Laser particle size analyzer, purchased from zhushai physical optical instruments ltd, model: LT 3600.

Three temperature zone tube furnace, purchased from shanghai army experimental facilities ltd, model: HTF-1200 III.

Isostatic press, purchased from mixtare technologies ltd, model: YLJ-CIP-15; the tabletting mold is purchased from combined fertilizer science crystal material technology ltd, model: Die-SP 20; conductivity test kit, purchased from mixcrystal materials technology ltd, model: EQ-PSC.

The high-energy ball mill is purchased from Texas Germany instruments and Equipment Co., Ltd, and has a model of DECO-PBM-V-0.4L.

BTS-5V10mA Battery testing equipment, which is purchased from Shenzhen New Wille electronics, Inc.

Transmission electron microscopy, purchased from Zeiss, germany.

Energy dispersive X-ray fluorescence spectrometer, available from hitachi.

Reagent:

Li₂S、GeS₂、SiS₂、SnS₂、LiCl、LiBr、LiI、P₂S₅are all purchased from Shanghai Aladdin Biotechnology, Inc.

Li_1.4Al_0.4Ti_1.6(PO₄)₃Purchased from mixcrystal technology materials ltd.

The present invention will be described in more detail below with reference to examples and comparative examples, but the technical scope of the present invention is not limited to these examples. All percentages, parts and ratios used in the present invention are based on mass unless otherwise specified.

Example 1

(mono) Li₆PS₅Preparation of Cl (LPSC) sulfide solid electrolyte particles

1. In a glove box under argon atmosphere, Li₂S、P₂S₅LiCl was added in a molar ratio of 5: 1: 2 to give 6.0g of a mixed powder. Zirconia balls with the diameter of 10mm are used for ball milling, the ball milling speed is set to be 300rpm, the ball milling time is 30 hours, and the mass ratio of the balls to the materials is 40: 1. And grinding the powder subjected to ball milling in a mortar to enable the powder to be fine and smooth.

2. And (3) pouring the powder obtained in the step (1) into a tabletting mold, and tabletting by using an isostatic press, wherein the pressure is kept at 200MPa, and the pressure keeping time is 1min, so that a wafer with the diameter of 16mm is obtained.

3. And moving the wafer into a crucible, putting the crucible into a tubular furnace in an argon atmosphere, heating to 550 ℃ at a temperature rising/reducing speed of 5 ℃/min, and sintering, wherein the heat preservation sintering time is 10h, and the flow rate of argon is 1.0L/min in the processes of rising, lowering and preserving heat.

4. After sintering, collecting Li after sintering₆PS₅Fully grinding the Cl block in a glove box, and sieving by using a sieve with the aperture of 30 mu m to obtain the Cl blockTo powdered Li₆PS₅Cl sulfide solid electrolyte particles 5.5 g. The particle diameter D is measured by a laser particle size analyzer_N50 is 0.5. mu.m.

(di) coated sulfide solid electrolyte LiNb_0.5Ta_0.5O₃Preparation of LPSC

1. 14.0mmol (0.0972g) of lithium metal was dissolved in 45.68g of anhydrous ethanol under an argon atmosphere, and 7.0mmol (2.8438g) of tantalum ethoxide and 7.0mmol (2.2275g) of niobium ethoxide were mixed to obtain a precursor solution.

2. Uniformly spraying the precursor solution on the Li prepared in the step (I)₆PS₅The spraying speed of the Cl sulfide solid electrolyte particles on the surface of 5.0g is 5g/min, and the spraying time is 1.5 min.

3. And (3) placing the sprayed solid electrolyte in a tubular furnace, heating to 120 ℃ at a heating rate of 5 ℃/min under the argon atmosphere, presintering for 2h at 120 ℃, then replacing the argon atmosphere with a pure oxygen atmosphere, heating to 500 ℃ at a heating rate of 5 ℃/min, and then sintering at 500 ℃ for 3h under the pure oxygen atmosphere. Then naturally cooling to room temperature to obtain powdery Li inside₆PS₅Cl sulfide solid electrolyte and LiNb on the surface_0.5Ta_0.5O₃Coated sulfide solid electrolyte LiNb of coating layer_0.5Ta_0.5O₃-LPSC。

Measuring the thickness of the oxide solid electrolyte layer to be 10.5nm by using a Transmission Electron Microscope (TEM), and measuring the coated sulfide solid electrolyte D by using a laser particle size analyzer_NThe 50 particle size was 0.53. mu.m.

Example 2

(mono) Li₃PS₄Preparation of (LPS) sulfide solid electrolyte particles

1. In a glove box under argon atmosphere, Li₂S、P₂S₅According to molar ratio 3:1, obtaining 6g of mixed powder, and carrying out ball milling by using 10mm zirconia balls, wherein the ball milling rotating speed is set to 400rpm, the ball milling time is 14h, and the ball-material mass ratio is 60: 1. And grinding the powder subjected to ball milling in a mortar to enable the powder to be fine and smooth.

2. Pouring the powder into a tabletting mold, and tabletting by using an isostatic press, wherein the pressure is kept at 200MPa for 1min to obtain a wafer with the diameter of 16 mm.

3. And moving the wafer into a crucible, and putting the crucible into a tubular furnace in an argon atmosphere, heating to 350 ℃ for sintering, wherein the heating/cooling speed is 2 ℃/min, the heat preservation time is 2h, and the flow rate of argon in the whole heating and cooling process is 1.0L/min.

4. After completion of the sintering, the block (LPS) collected after the sintering was ground in a glove box, and a powdery LPS sulfide solid electrolyte was obtained using a mesh having a pore size of 30 μm. The particle diameter D is measured by a laser particle size analyzer_N50 is 3.0. mu.m.

(di) coated sulfide solid electrolyte LiNb_0.15Ta_0.85O₃Preparation of LPS

1. 14.0mmol (0.0972g) of lithium metal was dissolved in 45.68g of anhydrous ethanol under an argon atmosphere, and 11.9mmol (4.834g) of tantalum ethoxide and 2.1mmol (0.668g) of niobium ethoxide were further mixed to obtain a precursor solution.

2. Uniformly spraying the precursor solution on the Li prepared in the step (I)₃PS₄5.0g of sulfide solid electrolyte particles, the spraying rate is 10g/min, and the spraying time is 2.6 min.

3. And (3) placing the sprayed solid electrolyte in a tubular furnace, heating to 120 ℃ at a heating rate of 5 ℃/min under the argon atmosphere, presintering for 2h at 120 ℃, then replacing the argon atmosphere with a pure oxygen atmosphere, heating to 500 ℃ at a heating rate of 5 ℃/min, and then sintering at 500 ℃ for 3h under the pure oxygen atmosphere. Then naturally cooling to room temperature to obtain powdery Li inside₃PS₄Sulfide solid electrolyte and LiNb on the surface_0.15Ta_0.85O-coated sulfide solid electrolyte LiNb_0.15Ta_0.85O₃-LPS。

The thickness of the oxide solid electrolyte layer was measured to be 38.6nm using a transmission electron microscope TEM. Measuring the coated sulfide solid electrolyte D by a laser particle size analyzer_NThe 50 particle size was 3.08. mu.m.

Example 3

(mono) Li₁₀GeP₂S₁₂Preparation of (LGPS) sulfide solid electrolyte particles

1. In a glove box under argon atmosphere, Li₂S、P₂S₅And GeS₂According to molar ratio 5: 1: 1, obtaining 6g of mixed powder, and carrying out ball milling by using 10mm zirconia balls, wherein the ball milling rotating speed is set to 450rpm, the ball milling time is 14h, and the ball-material mass ratio is 60: 1. And grinding the powder subjected to ball milling in a mortar to enable the powder to be fine and smooth.

2. Pouring the powder into a tabletting mold, and tabletting by using an isostatic press, wherein the pressure is kept at 200MPa for 1min to obtain a wafer with the diameter of 16 mm.

3. And moving the wafer into a crucible, putting the crucible into a tubular furnace in an argon atmosphere, heating to 550 ℃ for sintering, wherein the heating mode is that the temperature is increased to 500 ℃ at the rate of 5 ℃/min, then the temperature is increased to 550 ℃ at the rate of 2 ℃/min, the heat preservation time is 8h, the cooling rate is 5 ℃/min, and the flow rate of argon in the whole temperature increasing and decreasing process is 1.0L/min.

4. After completion of sintering, the sintered collected block (LGPS) was ground in a glove box, and a powdered LGPS sulfide solid electrolyte was obtained using a mesh with a pore size of 30 μm. D is measured by a laser particle size analyzer_NThe 50 particle size was 1.0. mu.m.

(di) coated sulfide solid electrolyte LiNb_0.85Ta_0.15Preparation of O-LGPS

1. 14.0mmol (0.0972g) of lithium metal was dissolved in 45.68g of anhydrous ethanol under an argon atmosphere, and 2.1mmol (0.853g) of tantalum ethoxide and 11.9mmol (3.787g) of niobium ethoxide were further mixed to obtain a precursor solution.

2. Uniformly spraying the precursor solution on the Li prepared in the step (I)₁₀GeP₂S₁₂The spraying speed of the surface of the sulfide solid electrolyte particles is 6g/min, and the spraying time is 1 min.

3. Placing the sprayed solid electrolyte in a tube furnace, heating to 120 ℃ at a heating rate of 5 ℃/min under the argon atmosphere, presintering for 2h at 120 ℃, and then changing the argon atmosphere to a more argon atmosphereChanging to pure oxygen atmosphere, heating to 500 ℃ at the heating speed of 5 ℃/min, and then sintering at 500 ℃ for 3h in the pure oxygen atmosphere. Then naturally cooling to room temperature to obtain powdery Li inside₁₀GeP₂S₁₂Sulfide solid electrolyte and LiNb on the surface_0.85Ta_0.15O-coated sulfide solid electrolyte LiNb_0.85Ta_0.15O-LGPS。

The thickness of the oxide solid electrolyte layer was measured to be 8.5nm using a transmission electron microscope TEM. Measuring the coated sulfide solid electrolyte D by a laser particle size analyzer_NThe 50 particle size was 1.01. mu.m.

Example 4

(mono) Li_5.5PS_4.5Br_1.5Preparation of (LPSB) sulfide solid electrolyte particles

1. In a glove box under argon atmosphere, Li₂S、P₂S₅LiBr in mol ratio 4: 1: 3 to give 6.0g of a mixed powder. Zirconia balls with the diameter of 10mm are used for ball milling, the ball milling speed is set to be 300rpm, the ball milling time is 20 hours, and the ball-material mass ratio is 30: 1. And grinding the powder subjected to ball milling in a mortar to enable the powder to be fine and smooth.

2. And (3) pouring the powder obtained in the step (1) into a tabletting mold, and tabletting by using an isostatic press, wherein the pressure is kept at 350MPa, and the pressure keeping time is 1min, so that a wafer with the diameter of 16mm is obtained.

3. And moving the wafer into a crucible, and putting the crucible into a tubular furnace in an argon atmosphere to heat to 450 ℃ for sintering, wherein the heating/cooling speed is 3 ℃/min, the heat preservation time is 10h, and the flow rate of argon in the whole heating and cooling process is 1.0L/min.

4. After completion of sintering, the block collected after sintering (LPSB) was ground in a glove box, and a powdery LPSB sulfide solid electrolyte was obtained using a mesh having a pore size of 30 μm. D is measured by a laser particle size analyzer_NThe 50 particle size was 1.5. mu.m.

(di) coated sulfide solid electrolyte LiNb_0.25Ta_0.75Preparation of O-LPSB

1. 14.0mmol (0.0972g) of lithium metal was dissolved in 45.68g of anhydrous ethanol under an argon atmosphere, and 10.5mmol (4.265g) of tantalum ethoxide and 3.5mmol (1.114g) of niobium ethoxide were mixed to obtain a precursor solution.

2. Uniformly spraying the precursor solution on the Li prepared in the step (I)_5.5PS_4.5Br_1.5The spraying speed of the surface of the sulfide solid electrolyte particles is 15g/min, and the spraying time is 3 min.

3. And (3) placing the sprayed solid electrolyte in a tubular furnace, heating to 120 ℃ at a heating rate of 5 ℃/min under the argon atmosphere, presintering for 2h at 120 ℃, then replacing the argon atmosphere with a pure oxygen atmosphere, heating to 600 ℃ at a heating rate of 5 ℃/min, and then sintering at 600 ℃ for 3h under the pure oxygen atmosphere. Then naturally cooling to room temperature to obtain powdery Li inside_5.5PS_4.5Br sulfide solid electrolyte and LiNb on the surface_0.25Ta_0.75O-coated sulfide solid electrolyte LiNb_0.25Ta_0.75O-LPSB。

The thickness of the oxide solid electrolyte layer was measured to be 68.7nm using transmission electron microscopy TEM. Measuring the particle diameter D of the coated sulfide solid electrolyte by a laser particle size analyzer_N50 was 1.63. mu.m.

Example 5

(mono) Li_10.5Sn_1.5P_1.5S₁₂Preparation of sulfide solid electrolyte particles

1. In a glove box under argon atmosphere, Li₂S、P₂S₅、SnS₂According to molar ratio of 5.25: 0.75: 1.5 to obtain 6.0g of a mixed powder. Zirconia balls with the diameter of 10mm are used for ball milling, the ball milling speed is set to be 450rpm, the ball milling time is 15 hours, and the ball-material mass ratio is 10: 1. And grinding the powder subjected to ball milling in a mortar to enable the powder to be fine and smooth.

3. And moving the wafer into a crucible, and putting the crucible into a tubular furnace in an argon atmosphere, heating to 400 ℃ for sintering, wherein the heating/cooling speed is 3.5 ℃/min, the heat preservation time is 15h, and the flow rate of argon in the whole heating and cooling process is 1.0L/min.

4. After the sintering, the block (LSPS) collected after sintering was ground in a glove box, and a powdery LSPS sulfide solid electrolyte was obtained using a mesh having a pore size of 30 μm. D is measured by a laser particle size analyzer_NThe 50 particle size was 1.5. mu.m.

(di) coated sulfide solid electrolyte LiNb_0.75Ta_0.25Preparation of O-LSPS

1. 14.0mmol (0.0972g) of lithium metal was dissolved in 45.68g of anhydrous ethanol under an argon atmosphere, and 3.5mmol (1.422g) of tantalum ethoxide and 10.5mmol (3.341g) of niobium ethoxide were further mixed to obtain a precursor solution.

2. Uniformly spraying the precursor solution on the Li prepared in the step (I)_10.5Sn_1.5P_1.5S₁₂The spraying speed of the surface of the sulfide solid electrolyte particles is 6g/min, and the spraying time is 5 min.

3. And (3) placing the sprayed solid electrolyte in a tubular furnace, heating to 120 ℃ at a heating rate of 5 ℃/min under the argon atmosphere, presintering for 2h at 120 ℃, then replacing the argon atmosphere with a pure oxygen atmosphere, heating to 500 ℃ at a heating rate of 5 ℃/min, and then sintering at 500 ℃ for 3h under the pure oxygen atmosphere. Then naturally cooling to room temperature to obtain powdery Li inside_10.5Sn_1.5P_1.5S₁₂Sulfide solid electrolyte and LiNb on the surface_0.75Ta_0.25O-coated sulfide solid electrolyte LiNb_0.75Ta_0.25O-LSPS。

The thickness of the oxide solid electrolyte layer was measured to be 50.6nm using a transmission electron microscope TEM. Measuring the coated sulfide solid electrolyte D by a laser particle size analyzer_NThe 50 particle size was 1.60. mu.m.

Example 6

(mono) Li_9.5Si_0.5P_2.5S₁₂Of (LSiPS) sulfide solid electrolyte particlesPreparation of

1. In a glove box under argon atmosphere, Li₂S、P₂S₅、SiS₂According to a molar ratio of 9.5: 2.5: 1.0 to obtain 6.0g of a mixed powder. Zirconia balls with the diameter of 10mm are used for ball milling, the ball milling speed is set to be 450rpm, the ball milling time is 10 hours, and the ball-material mass ratio is 10: 1. And grinding the powder subjected to ball milling in a mortar to enable the powder to be fine and smooth.

2. And (3) pouring the powder obtained in the step (1) into a tabletting mold, and tabletting by using an isostatic press, wherein the pressure is kept at 300MPa, and the pressure keeping time is 1min, so that a wafer with the diameter of 16mm is obtained.

3. And moving the wafer into a crucible, and putting the crucible into a tubular furnace in an argon atmosphere to heat to 450 ℃ for sintering, wherein the heating/cooling speed is 4 ℃/min, the heat preservation time is 12h, and the flow rate of argon in the whole heating and cooling process is 1.0L/min.

4. After the sintering, the block (LSiPS) collected after sintering was ground in a glove box, and a powdery LSiPS sulfide solid electrolyte was obtained using a mesh having a pore size of 30 μm. D is measured by a laser particle size analyzer_NThe 50 particle size was 1.25. mu.m.

Preparation of (di) coated sulfide solid electrolyte LATP-LSiPS

1. Preparing a target material: taking 15g of Li_1.4Al_0.4Ti_1.6(PO₄)₃The solid electrolyte powder was ground with 1% binder (PVA) to mix well, and then the mixture was sheeted at 300kg/cm²The powder is pressed in a copper mould with the diameter of 50mm to prepare the copper back target material with the thickness of 2.5 mm.

2. Preparation of a coating layer: adopting a radio frequency magnetron sputtering method, wherein the parameters of magnetron sputtering are as follows: the vacuum degree of the chamber is 1.0 multiplied by 10^-4Pa, argon as working atmosphere, 7cm of target spacing, 35sccm of gas flow, 0.25Pa of working pressure, 100min of sputtering time, 100W of sputtering power, room temperature of substrate, and Li_9.5Si_0.5P_2.5S₁₂(LSiPS) sulfide solid electrolyte surface construction Li_1.4Al_0.4Ti_1.6(PO₄)₃(LATP) coating layer to obtain coated sulfide solid electrolyte LATP-LSiPS.

The thickness of the oxide solid electrolyte layer was measured to be 9.8nm using a transmission electron microscope TEM. Measuring the coated sulfide solid electrolyte D by a laser particle size analyzer_NThe 50 particle size was 1.28. mu.m.

Example 7

(mono) Li₁₀GeP₂S₁₂Preparation of (LGPS) sulfide solid electrolyte particles

The preparation method is the same as that of the step (one) in the example 3.

Preparation of (di) coated sulfide solid electrolyte LiPON-LGPS

1. Preparing a target material: taking 15g of Li₃PO₄Grinding with 1% binder (PVA), mixing, and tabletting with 300kg/cm²The powder is pressed in a copper mould with the diameter of 50mm to prepare the copper back target material with the thickness of 2.5 mm.

2. Preparation of a coating layer: adopting a radio frequency magnetron sputtering method, wherein the parameters of magnetron sputtering are as follows: the vacuum degree of the chamber is 10.0 multiplied by 10^-4Pa, working atmosphere is nitrogen: argon gas is 3:1, the target distance is 7cm, the gas flow is 35sccm, the working pressure is 0.9Pa, the sputtering time is 300min, the sputtering power is 300W, the substrate temperature is room temperature, and in Li₁₀GeP₂S₁₂And (LGPS) sulfide solid electrolyte surface constructing a LiPON coating layer to obtain a coated sulfide solid electrolyte LiPON-LGPS.

The thickness of the oxide solid electrolyte layer was measured to be 95.3nm using a transmission electron microscope TEM. The content of element components of the oxide solid electrolyte layer is tested by using an energy dispersion X-ray fluorescence spectrometer (test condition), and the molecular formula of the LiPON is Li_3.3PO_3.9N_0.17. Measuring the coated sulfide solid electrolyte D by a laser particle size analyzer_NThe 50 particle size was 1.25. mu.m.

Example 8

(mono) Li₆PS₅Preparation of Cl (LPSC) sulfide solid electrolyte particlesPrepare for

2. And (3) pouring the powder obtained in the step (1) into a tabletting mold, and tabletting by using an isostatic press, wherein the pressure is kept at 100MPa, and the pressure keeping time is 1min, so that a wafer with the diameter of 16mm is obtained.

3. And moving the wafer into a crucible, putting the crucible into a tubular furnace in an argon atmosphere, heating to 600 ℃ at a temperature rising/reducing speed of 3 ℃/min, and sintering, wherein the heat preservation sintering time is 6h, and the flow rate of argon is 1.0L/min in the processes of rising, lowering and preserving heat.

4. After sintering, collecting Li after sintering₆PS₅The Cl blocks were ground thoroughly in a glove box and sieved using a 30 μm mesh screen to give powdered Li₆PS₅Cl sulfide solid electrolyte particles. The particle size DN50 was 2.0 μm as determined by laser particle size analyzer.

(di) coated sulfide solid electrolyte LiNb_0.5Ta_0.5O₃Preparation of LPSC

2. Uniformly spraying the precursor solution on the Li prepared in the step (I)₆PS₅And the spraying speed of the Cl sulfide solid electrolyte particle surface is 5g/min, and the spraying time is 2 min.

3. Placing the sprayed solid electrolyte in a tube furnace, heating to 120 ℃ at a heating rate of 5 ℃/min under the argon atmosphere, presintering for 2h at 120 ℃, then replacing the argon atmosphere with a pure oxygen atmosphere, heating to 200 ℃ at a heating rate of 5 ℃/min, and then carrying out heat preservation and burning at 200 ℃ under the pure oxygen atmosphereKnot 2 h. Then naturally cooling to room temperature to obtain powdery Li inside₆PS₅Cl sulfide solid electrolyte and LiNb on the surface_0.5Ta_0.5O₃Coated sulfide solid electrolyte LiNb of coating layer_0.5Ta_0.5O₃-LPSC。

Measuring the thickness of the oxide solid electrolyte layer to be 17.5nm by using a Transmission Electron Microscope (TEM), and measuring the coated sulfide solid electrolyte D by using a laser particle size analyzer_NThe 50 particle size was 2.04. mu.m.

Example 9

(mono) Li₆PS₅Preparation of Cl (LPSC) sulfide solid electrolyte particles

2. And (3) pouring the powder obtained in the step (1) into a tabletting mold, and tabletting by using an isostatic press, wherein the pressure is kept at 1000MPa, and the pressure keeping time is 1min, so that a wafer with the diameter of 16mm is obtained.

3. And moving the wafer into a crucible, putting the crucible into a tubular furnace in an argon atmosphere, heating to 450 ℃ at a temperature rising/reducing speed of 3 ℃/min, and sintering, wherein the heat preservation sintering time is 15h, and the flow rate of argon is 1.0L/min in the processes of rising, lowering and preserving heat.

4. After sintering, collecting Li after sintering₆PS₅The Cl blocks were ground thoroughly in a glove box and sieved using a 30 μm mesh screen to give powdered Li₆PS₅Cl sulfide solid electrolyte particles. The particle diameter D is measured by a laser particle size analyzer_N50 is 2.8. mu.m.

(di) coated sulfide solid electrolyte LiNb_0.5Ta_0.5O₃Preparation of LPSC

2. Uniformly spraying the precursor solution on the Li prepared in the step (I)₆PS₅The spraying speed of the Cl sulfide solid electrolyte particle surface is 15g/min, and the spraying time is 5 min.

3. And (3) placing the sprayed solid electrolyte in a tubular furnace, heating to 120 ℃ at a heating rate of 5 ℃/min under the argon atmosphere, presintering for 2h at 120 ℃, then replacing the argon atmosphere with a pure oxygen atmosphere, heating to 400 ℃ at a heating rate of 5 ℃/min, and then sintering at 400 ℃ for 1h under the pure oxygen atmosphere. Then naturally cooling to room temperature to obtain powdery Li inside₆PS₅Cl sulfide solid electrolyte and LiNb on the surface_0.5Ta_0.5O₃Coated sulfide solid electrolyte LiNb of coating layer_0.5Ta_0.5O₃-LPSC。

Measuring the thickness of the oxide solid electrolyte layer to be 99.6nm by using a Transmission Electron Microscope (TEM), and measuring the coated sulfide solid electrolyte D by using a laser particle size analyzer_NThe 50 particle size was 3.0. mu.m.

Comparative example 1

Preparation of Li₆PS₅Cl (lpsc) sulfide solid electrolyte particles were prepared in the same manner as in the step (one) of example 1.

Comparative example 2

Preparation of Li₃PS₄(LPS) sulfide solid electrolyte particles were prepared in the same manner as in the step (one) of example 2.

Comparative example 3

Preparation of Li₁₀GeP₂S₁₂(LGPS) sulfide solid electrolyte particles were prepared in the same manner as in the step (one) of example 3.

Comparative example 4

(mono) Li₆PS₅Preparation of Cl (LPSC) sulfide solid electrolyte particles

The preparation method is the same as the step (one) in the example 1

(II) coated sulfide solid electrolyte LiNbO₃Preparation of LPSC

1. 100mg of lithium metal (14.0mmol) was dissolved in 45.68g of anhydrous ethanol under an argon atmosphere, and 4.455g of niobium ethoxide (14.0mmol) was further mixed to obtain a precursor solution.

2. Spraying the precursor solution on Li₆PS₅And the spraying speed of the Cl sulfide solid electrolyte surface is 5g/min, and the spraying time is 1.5 min.

3. And (3) placing the sprayed solid electrolyte in a tubular furnace, heating to 120 ℃ at a heating rate of 5 ℃/min under the argon atmosphere, presintering for 2h at 120 ℃, then replacing the argon atmosphere with a pure oxygen atmosphere, heating to 500 ℃ at a heating rate of 5 ℃/min, and then sintering at 500 ℃ for 3h under the pure oxygen atmosphere. Then naturally cooling to room temperature to obtain Li in the interior₆PS₅Cl sulfide solid electrolyte and LiNbO on the surface₃Coated sulfide solid electrolyte powder LNO-LPSC of the coating layer.

The thickness of the oxide solid electrolyte layer was measured to be 11.5nm using a transmission electron microscope TEM. Measuring the coated sulfide solid electrolyte D by a laser particle size analyzer_NThe 50 particle size was 0.55. mu.m.

Comparative example 5

(mono) Li₆PS₅Preparation of Cl (LPSC) sulfide solid electrolyte particles

The preparation method is the same as the step (one) in the example 1.

(di) coated sulfide solid electrolyte LiTaO₃Preparation of LPSC

1. 100mg of lithium metal (14.0mmol) was dissolved in 45.68g of anhydrous ethanol under an argon atmosphere, and 5.687g of tantalum ethoxide (14.0mmol) was further mixed to obtain a precursor solution.

2. Spraying the precursor solution on Li₆PS₅And the spraying speed of the Cl sulfide solid electrolyte surface is 5g/min, and the spraying time is 1.5 min.

3. Placing the sprayed solid electrolyte in a tube furnace, and heating at a heating rate of 5 ℃ in an argon atmosphereHeating to 120 ℃ per min, pre-sintering for 2h at 120 ℃, then replacing the argon atmosphere with a pure oxygen atmosphere, heating to 500 ℃ at a heating speed of 5 ℃/min, and then sintering for 3h at 500 ℃ in a pure oxygen atmosphere. Then naturally cooling to room temperature to obtain Li in the interior₆PS₅Cl sulfide solid electrolyte with LiTaO on the surface₃And the coating sulfide solid electrolyte powder LTO-LPSC of the coating layer.

The thickness of the oxide solid electrolyte layer was measured to be 12.0nm using a transmission electron microscope TEM. Measuring the coated sulfide solid electrolyte D by a laser particle size analyzer_NThe 50 particle size was 0.54. mu.m.

Comparative example 6

(mono) Li₆PS₅Preparation of Cl (LPSC) sulfide solid electrolyte particles

The preparation method is the same as the step (one) in the example 1.

(di) coated sulfide solid electrolyte LiNb_0.5Ta_0.5O₃Preparation of LPSC

The difference from the step (II) in example 1 is that the spray coating time is 0.5 min; obtaining powdery Li in the interior₆PS₅Cl sulfide solid electrolyte and LiNb on the surface_0.5Ta_0.5O₃Coated sulfide solid electrolyte LiNb of coating layer_0.5Ta_0.5O₃-an LPSC; measuring the thickness of the oxide solid electrolyte layer to be 3.4nm by using a Transmission Electron Microscope (TEM), and measuring the coated sulfide solid electrolyte D by using a laser particle size analyzer_NThe 50 particle size was 0.51. mu.m.

Comparative example 7

(mono) Li₃PS₄Preparation of (LPS) sulfide solid electrolyte particles

The preparation method is the same as the step (one) in the example 2.

(di) coated sulfide solid electrolyte LiNb_0.15Ta_0.85O₃Preparation of LPS

The difference from the step (II) in example 2 is that the spray coating rate is 10g/min, and the spray coating time is 10 min; obtaining powdery Li in the interior₃PS₄Sulfide solid electrolyte and LiNb on the surface_0.15Ta_0.85O-coated sulfide solid electrolyte LiNb_0.15Ta_0.85O₃-LPS; the thickness of the oxide solid electrolyte layer was measured to be 140.6nm using a transmission electron microscope TEM. Measuring the coated sulfide solid electrolyte D by a laser particle size analyzer_NThe 50 particle size was 3.26. mu.m.

Experimental example 1

The initial ionic conductivity, the ionic conductivity after dry air exposure, and hydrogen sulfide (H) of examples 1 to 9 and comparative examples 1 to 7 were measured as follows₂S) production amount.

(1) Initial ionic conductivity test

The products obtained in examples 1 to 9 and comparative examples 1 to 7 were put into a tabletting mold in a glove box replaced with fully dried argon (dew point-60 ℃ or lower), tabletted by an isostatic press at a pressure of 200MPa and a dwell time of 1.5min, and demolded to obtain a solid electrolyte sheet. The thickness of the solid electrolyte sheet was measured using a digital micrometer. And (3) taking a stainless steel wafer with the diameter of 16mm as a blocking electrode, packaging the solid electrolyte sheet by using a conductivity test kit, and performing EIS test by using an electrochemical workstation.

The EIS test method is as follows: applying a voltage of 50mV in a frequency range of 1Hz to 1MHz by an alternating current impedance method; the ionic conductivity σ was calculated using the equation σ ═ L/RS, where R is the total resistance of the solid electrolyte sheet, L is the thickness of the solid electrolyte sheet, and S is the area of a single surface of the solid electrolyte sheet, and the test results are shown in table 1.

(2) Determination of the Ionic conductivity after Dry air Exposure

The products obtained in examples 1 to 9 and comparative examples 1 to 7 were left to stand for 4 hours in a glove box which was replaced with dry air having a dew point of-45 c, and then placed again in a glove box which was replaced with Ar gas after sufficient drying (dew point-60 c or less), and the ionic conductivity after exposure to dry air was measured by the same test method as the initial ionic conductivity test, and the test results are shown in table 1.

(3) VulcanizationHydrogen (H)₂S) measurement of production amount

100mg of the products obtained in examples 1 to 9 and comparative examples 1 to 7 above were weighed in a glove box replaced with dry air having a dew point of-60 ℃ and placed in a volume of 1755cm³The concentration of hydrogen sulfide in the dryer (temperature: 25 ℃ C., humidity: 30%) was measured by a hydrogen sulfide detector (SK-800-H2S, manufactured by Ningying, Ltd.) for 300 seconds, the volume of hydrogen sulfide was calculated, the amount of hydrogen sulfide produced was determined, and the calculation results are shown in Table 1.

TABLE 1 Performance index of the products obtained in examples 1 to 9 and comparative examples 1 to 7

Experimental example 2

The application performance of the samples prepared in examples 1 to 9 and comparative examples 1 to 7 in the solid-state lithium battery was evaluated in the following manner, that is, the negative electrode plate, the solid-state electrolyte plate and the positive electrode plate were first prepared, then the solid-state battery was fabricated, and finally the battery performance was tested.

Preparing a negative pole piece

1. Metal lithium negative pole piece: in a vacuum glove box, a metallic lithium negative electrode disk having a diameter of 12mm, which is a negative electrode active material and negative electrode current collector, was cut out.

2. Lithium-indium alloy negative pole piece: in a vacuum glove box, a lithium-indium alloy negative electrode disk with the diameter of 12mm is cut, and the lithium-indium alloy negative electrode disk is a negative electrode active material and a negative electrode current collector.

3. Negative pole piece containing coated sulfide solid electrolyte

In an environment with a dew point of-30 ℃, a conductive agent (Super P), a binder (PVDF), a negative electrode active material (SiO/graphite (SiO mass ratio of 10%)), and the coated sulfide solid electrolyte prepared in example 3 were mixed in a mass ratio of 0.5: 0.5: 7.5: 1.5 in N-methylpyrrolidone (NMP) solvent to prepare negative active slurry. And coating the negative active slurry on a copper foil, carrying out vacuum drying at 80 ℃, and then carrying out rolling slicing to obtain a negative pole piece with the diameter of 12mm, which is recorded as CE-S3.

(II) preparation of solid electrolyte sheet

Samples prepared in comparative examples 1 to 7 of examples 1 to 9, respectively, were placed in a mold and prepared into solid electrolyte sheets having a thickness of 100 μm and a diameter of 16mm by applying a pressure of 100MPa, and were designated SSE-S1, SSE-S2, SSE-S3, SSE-S4, SSE-S5, SSE-S6, SSE-S7, SSE-S8, SSE-S9, SSE-C1, SSE-C2, SSE-C3, SSE-C4, SSE-C5, SSE-C6 and SSE-C7, respectively.

(III) preparing the positive pole piece

1.5 parts by mass of each of the samples prepared in examples 1 to 9 and comparative examples 1 to 7 was weighed in an environment having a dew point of-30 ℃, and then added to an organic solvent N-methylpyrrolidone (NMP) together with 0.5 part by mass of a conductive agent (Super P), 0.5 part by mass of a binder (PVDF), and 7.5 parts by mass of a positive electrode active material (lithium cobaltate), ground, and mixed uniformly to obtain a positive electrode active slurry. And uniformly coating the positive active slurry on the surface of the carbon-coated aluminum foil of the positive current collector to form a positive active layer, carrying out vacuum drying at 80 ℃, rolling, and cutting to obtain a positive pole piece with the diameter of 10mm, which is respectively marked as PE-S1, PE-S2, PE-S3, PE-S4, PE-S5, PE-S6, PE-S7, PE-S8, PE-S9, PE-C1, PE-C2, PE-C3, PE-C4, PE-C5, PE-C6 and PE-C7.

(IV) assembling the solid-state battery:

and respectively selecting the prepared positive pole piece, the prepared solid electrolyte piece and the prepared negative pole piece, sequentially laminating and applying 500MPa pressure for cold pressing to obtain a solid battery, marking as BA-S1, BA-S2, BA-S3, BA-S4, BA-S5, BA-S6, BA-S7, BA-S8, BA-S9, BA-C1, BA-C2, BA-C3, BA-C4, BA-C5, BA-C6 and BA-C7, and testing the assembled battery according to the following method, wherein the combination mode of the positive pole piece, the solid electrolyte piece and the negative pole piece is shown in table 2, and the test result is shown in table 3.

1. First charge and discharge performance

The solid-state battery prepared above was subjected to constant-current charging at a current density of 0.2C to 4.5V at 25C using a BTS-5V10mA battery test cabinet, then to constant-voltage charging at a voltage of 4.5V to a cutoff current of 0.02C, and to discharge at 0.2C to 2.4V to obtain the first-cycle specific charge-discharge capacity.

2. Cyclic character

After the solid-state battery prepared above was activated at 25 ℃ using a BTS-5V10mA battery test cabinet, it was charged to 4.5V at a constant current and constant voltage of 0.5C, and the current was cut off at 0.02C, left for 5min, and then discharged to 2.4V at a constant current of 0.5C, left for 5 min. According to the circulation, after 100 times of charge and discharge circulation, the discharge specific capacity of the 100 th circulation is calculated.

3. Multiplying power test

The solid-state battery prepared above was charged at constant current and constant voltage of 0.2C to 4.5V, with a cutoff current of 0.02C, at 25 ℃ for 5min using a BTS-5V10mA battery test cabinet, discharged at 0.2C to 2.4V at 25 ℃, and the 0.2C specific discharge capacity of the battery was recorded for 5 min. Charging to 4.5V with 0.2C constant current and constant voltage, stopping current at 0.02C, standing for 5min, discharging to 2.5V with 1C, and recording the 1C specific discharge capacity. Then, the mixture was charged to 4.5V at a constant current and a constant voltage of 0.2C, the current was cut off at 0.02C, left for 5min, and discharged to 2.5V at 3C, and the 3C specific discharge capacity was recorded. And finally, charging to 4.5V at a constant current and a constant voltage of 0.2C, stopping the current at 0.02C, standing for 5min, discharging to 2.5V at 5C, and recording the 5C specific discharge capacity.

Table 2 manner of assembling the solid-state battery.

Table 3 solid state battery performance test results

With respect to the coated sulfide solid electrolytes prepared in examples 1 to 9, as compared with the uncoated sulfide solid electrolytes in comparative examples 1 to 3, it can be seen from table 1 that the hydrogen sulfide gas generation amount of the coated sulfide solid electrolyte of the present invention is much lower than that of the uncoated sulfide solid electrolyte, and the degree of attenuation of the ion conductivity after exposure to dry air for 4 hours is significantly lower than that of comparative examples 1 to 3; as can be seen from table 3, the battery test results show that, compared with the battery containing the uncoated sulfide solid electrolyte, the battery containing the coated sulfide solid electrolyte of the present invention has significantly increased first cycle charge specific capacity, first cycle discharge specific capacity, discharge specific capacity after 100 cycles of cycling, and rate capability.

Therefore, the surface of the specific sulfide solid electrolyte particle is coated with a layer of specific oxide solid electrolyte with high environmental stability, so that direct contact between environmental moisture and the sulfide solid electrolyte can be effectively prevented, the electrochemical stability of the sulfide solid electrolyte is greatly improved, and the problem of unmatched electrochemical windows when the sulfide solid electrolyte particle is mixed with a positive electrode material for use is solved.

With respect to the coated sulfide solid electrolytes prepared in examples 1 to 9, and the coated LiNbO in comparative examples 4 to 5₃Or LiTaO₃In comparison with the coated sulfide solid electrolyte of (1), it is clear from Table 1 that the amount of hydrogen sulfide gas generated in the coated sulfide solid electrolyte of the present invention is far lower than that in the case where the coating layer is LiNbO₃Or LiTaO₃The coated sulfide solid electrolyte has obviously lower degree of attenuation of the ionic conductivity after being exposed in dry air for 4 hours than that of the comparative example 4-5; as can be seen from Table 3, the results of the battery tests showed that LiNbO was included as the coating layer₃Or LiTaO₃Compared with the coated sulfide solid electrolyte battery, the battery containing the coated sulfide solid electrolyte has obviously improved first cycle charging specific capacity, first cycle discharging specific capacity, discharging specific capacity after 100 cycles of cycle and rate capability.

Further proves that in the invention, LiNb is synergistic with tantalum element_xTa_1-xO₃(x is more than or equal to 0.15 and less than or equal to 0.85) ensures that the stability of the solid electrolyte to water and oxygen is better than that of LiNbO₃And LiTaO₃Can improve the electrochemical stability of the sulfide solid electrolyte, and is obviously superior to LiNbO in the aspects of improving the cycle performance and the rate performance of the battery₃And LiTaO₃。

As for the sulfide solid electrolyte in comparative example 6, in comparison with the coated sulfide solid electrolyte prepared in example 1, it is understood from table 1 that the thickness of the oxide solid electrolyte layer is too low to be lower than the preferable range of the present invention, and therefore, the amount of hydrogen sulfide gas generated is too large, and the degree of attenuation of the ionic conductivity after exposure to dry air for 4 hours becomes significantly large, which indicates that the electrochemical stability of the sulfide solid electrolyte cannot be improved at this time; as can be seen from table 3, the battery test results show that the thickness of the oxide solid electrolyte layer of the coated sulfide solid electrolyte is too low, and the first cyclic charge specific capacity, the first cyclic discharge specific capacity, and the discharge specific capacity and the rate capability after 100 cycles of cycling are significantly reduced.

With respect to the sulfide solid electrolyte in comparative example 7, in comparison with the coated sulfide solid electrolyte prepared in example 2, as can be seen from table 1, the thickness of the oxide solid electrolyte layer is too thick to be higher than the preferable range of the present invention, and although the electrochemical stability of the sulfide solid electrolyte is improved, as can be seen from table 3, the battery test results show that the thickness of the oxide solid electrolyte layer of the coated sulfide solid electrolyte is too thick, and the first cycle specific charge capacity, the first cycle specific discharge capacity, the specific discharge capacity after 100 cycles and the rate capability thereof are significantly reduced. The reason is that the thickness of the oxide solid electrolyte layer is too thick, and the ionic conductivity of the oxide solid electrolyte is lower than that of the sulfide solid electrolyte, so that the ionic conductivity of the whole solid electrolyte is obviously reduced, the internal resistance is increased, the ionic transmission performance is influenced, the cycle performance is not facilitated, the charge-discharge specific capacity and the cycle performance are reduced, and the rate discharge performance is seriously reduced.

The foregoing is considered as illustrative and not restrictive in character, and that various modifications, equivalents, and improvements made within the spirit and principles of the invention are intended to be included within the scope of the invention.

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Coated sulfide solid electrolyte and preparation method and application thereof

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