阅读说明：本技术 固体电解质材料和使用它的电池 (Solid electrolyte material and battery using the same ) 是由 田中良明 上野航辉 浅野哲也 酒井章裕 于 2019-10-31 设计创作，主要内容包括：本公开提供一种具有高的锂离子传导率的固体电解质材料。本公开的固体电解质材料包含Li、M、O和X,M是选自Nb和Ta中的至少一种元素,X是选自Cl、Br和I中的至少一种元素。(The present disclosure provides a solid electrolyte material having high lithium ion conductivity. The solid electrolyte material of the present disclosure contains Li, M, O, and X, M being at least one element selected from Nb and Ta, and X being at least one element selected from Cl, Br, and I.)

1. A solid electrolyte material comprising Li, M, O and X,

wherein the content of the first and second substances,

m is at least one element selected from Nb and Ta, and

x is at least one element selected from Cl, Br and I and contains Cl.

2. The solid electrolyte material according to claim 1,

m comprises Ta.

3. The solid electrolyte material according to claim 1 or 2,

the molar ratio of Ta to the total of Nb and Ta is 0.5 to 1.0.

4. The solid electrolyte material according to claim 3,

m is Ta.

5. The solid electrolyte material according to any one of claims 1 to 4,

contains a 1 st crystal phase, wherein the 1 st crystal phase has a peak in a 1 st range having a diffraction angle 2 theta of 11.05 DEG or more and 11.15 DEG or less in an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu-Kalpha rays.

6. The solid electrolyte material according to claim 5,

in the X-ray diffraction pattern, a peak derived from the 1 st crystal phase is present in the 2 nd range in which the value of the diffraction angle 2 θ is 17.85 ° or more and 17.96 ° or less.

7. The solid electrolyte material according to claim 5 or 6,

further comprising a 2 nd crystal phase different from the 1 st crystal phase.

8. The solid electrolyte material according to any one of claims 1 to 7,

the molar ratio Li/M of Li to M is 0.60 or more and 2.4 or less.

9. The solid electrolyte material according to claim 8,

the molar ratio Li/M is 0.96-1.20.

10. The solid electrolyte material according to any one of claims 1 to 9,

the molar ratio of O to X, O/X, is 0.16 or more and 0.35 or less.

11. The solid electrolyte material according to claim 10,

the molar ratio O/X is 0.31 or more and 0.35 or less.

12. A battery comprising a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode,

at least one selected from the group consisting of the positive electrode, the negative electrode and the electrolyte layer contains the solid electrolyte material according to any one of claims 1 to 11.

Technical Field

The present disclosure relates to a solid electrolyte material and a battery using the same.

Background

Patent document 1 discloses an all-solid battery using a sulfide solid electrolyte material.

Prior art documents

Patent document 1: japanese patent laid-open publication No. 2011-129312

Disclosure of Invention

Problems to be solved by the invention

An object of the present disclosure is to provide a solid electrolyte material having high lithium ion conductivity.

Means for solving the problems

The solid electrolyte material of the present disclosure contains Li, M, O, and X, wherein M is at least one element selected from Nb and Ta, and X is at least one element selected from Cl, Br, and I and contains Cl.

ADVANTAGEOUS EFFECTS OF INVENTION

The present disclosure provides a solid electrolyte material having high lithium ion conductivity.

Drawings

Fig. 1 shows a cross-sectional view of a battery 1000 according to embodiment 2.

Fig. 2 shows a cross-sectional view of an electrode material 1100 according to embodiment 2.

Fig. 3 shows a schematic view of a pressure forming die 300 for evaluating the ion conductivity of a solid electrolyte material.

Fig. 4 is a graph showing the temperature dependence of the ion conductivity of the solid electrolyte material of sample 1.

Fig. 5 is a graph showing X-ray diffraction patterns of the solid electrolyte materials of samples 1, 8 and 9.

FIG. 6 is a graph showing X-ray diffraction patterns of the solid electrolyte materials of samples 1 to 7.

Fig. 7 is a graph showing the initial discharge characteristics of the battery of sample 1.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

(embodiment 1)

The solid electrolyte material of embodiment 1 contains Li, M, O, and X, wherein M is at least one element selected from Nb and Ta, and X is at least one element selected from Cl, Br, and I, and contains Cl. The solid electrolyte material of embodiment 1 has high lithium ion conductivity.

The solid electrolyte material according to embodiment 1 can maintain high lithium ion conductivity in a range of a temperature range (for example, a range of-30 ℃ to 80 ℃) where a battery is expected to be used. Therefore, the battery using the solid electrolyte material of embodiment 1 can stably operate even in an environment where there is a temperature change.

From the viewpoint of safety, it is desirable that the solid electrolyte material of embodiment 1 does not contain sulfur. The sulfur-free solid electrolyte material does not generate hydrogen sulfide even when exposed to the atmosphere, and therefore is excellent in safety. Note that the sulfide solid electrolyte material disclosed in patent document 1 generates hydrogen sulfide if exposed to the atmosphere.

In order to improve the ion conductivity of the solid electrolyte material, M may contain Ta.

In order to improve the ion conductivity of the solid electrolyte material, the molar ratio of Ta to the total of Nb and Ta may be 0.5 or more and 1.0 or less. That is, the amount of material of Nb constituting M is represented by M_NbThe amount of substance of Ta constituting M is defined as M_TaThen, the following equation can be satisfied: m is more than or equal to 0.5_Ta/(m_Nb+m_Ta)≤1.0。

In order to further improve the ionic conductivity of the solid electrolyte material, the formula may be satisfied: m is_Ta/(m_Nb+m_Ta) 1.0. That is, M may be Ta.

The solid electrolyte material of embodiment 1 may be substantially composed of Li, M, O, and X. Here, "the solid electrolyte material of embodiment 1 is substantially composed of Li, M, O, and X" means that the molar ratio of the total amount of substances of Li, M, O, and X to the total amount of substances of all the elements constituting the solid electrolyte material of embodiment 1 is 90% or more. For example, the molar ratio may be 95% or more.

In order to improve the ionic conductivity of the solid electrolyte material, the solid electrolyte material of embodiment 1 may be composed of only Li, M, O, and X.

In order to improve the lithium ion conductivity of the solid electrolyte material, X may contain at least one element selected from bromine (i.e., Br) and iodine (i.e., I) and Cl. In this case, the molar ratio of the amount of Cl to the total amount of all the elements constituting X may be 30% or more.

In order to improve the lithium ion conductivity of the solid electrolyte material, X may be Cl.

The crystal may contain a 1 st crystal phase, and the 1 st crystal phase may have a peak in a 1 st range having a diffraction angle 2 θ of 11.05 ° or more and 11.15 ° or less in an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu — K α rays. The 1 st crystal phase has high lithium ion conductivity. The solid electrolyte material of embodiment 1 contains the 1 st crystal phase, and thus easily forms a path for lithium ion diffusion. As a result, the solid electrolyte material has high lithium ion conductivity.

X-ray diffraction using Cu-Ka radiation (wavelength: X)Andi.e., 0.15405nm and 0.15444nm) by the θ -2 θ method. The diffraction angle of a diffraction peak in an X-ray diffraction pattern is an angle indicating the maximum intensity of a mountain-shaped portion having an SN ratio (i.e., the ratio of signal S to background noise N) of 3 or more and a half-value width of 10 ° or less. The half-value width is defined as the maximum intensity of the diffraction peak is I_MAXWhen the intensity is I_MAXThe width represented by the difference between two angles of half the value of (a).

In the X-ray diffraction pattern of the 1 st crystal phase, a peak present in the 1 st range indicates, for example, the maximum intensity or the 2 nd maximum intensity.

In order to improve the ion conductivity of the solid electrolyte material, a peak derived from the 1 st crystal phase may be present not only in the 1 st range but also in the 2 nd range in which the value of the diffraction angle 2 θ is 17.85 ° or more and 17.96 ° or less in the X-ray diffraction pattern.

The solid electrolyte material of embodiment 1 may further contain a 2 nd crystal phase different from the 1 st crystal phase. That is, the crystal may further contain a 2 nd crystal phase having a peak at a diffraction angle 2 θ different from that of the 1 st crystal phase in an X-ray diffraction pattern. By containing the 2 nd crystal phase, lithium ion conduction between the 1 st crystal phases can be promoted. As a result, the solid electrolyte material has higher ion conductivity.

The 2 nd crystal phase is, for example, a crystal phase derived from LiCl.

The 2 nd crystal phase may be interposed between the 1 st crystal phase.

In order to improve the ion conductivity of the solid electrolyte material, the molar ratio Li/M of Li to M may be 0.60 or more and 2.4 or less. The preferable molar ratio Li/M may be 0.96 or more and 1.20 or less. By selecting the value of the molar ratio Li/M in this way, the Li concentration is optimized.

In order to improve the ion conductivity of the solid electrolyte material, the molar ratio O/X of O to X may be 0.16 or more and 0.35 or less. The molar ratio O/X may be preferably 0.31 or more and 0.35 or less. By selecting the value of the molar ratio O/X in this way, the 1 st crystal phase can be easily realized.

The shape of the solid electrolyte material of embodiment 1 is not limited. Examples of such shapes are needle-like, spherical or oval spherical. The solid electrolyte material of embodiment 1 may be particles. The solid electrolyte material of embodiment 1 may be formed to have a particle or plate shape.

When the solid electrolyte material of embodiment 1 is in the form of particles (for example, spheres), the median particle diameter of the solid electrolyte material may be 0.1 μm or more and 100 μm or less, or 0.5 μm or more and 10 μm or less. Thus, the solid electrolyte material of embodiment 1 has higher ion conductivity. In addition, the solid electrolyte material of embodiment 1 and other materials can be well dispersed.

The median diameter of the particles means a particle diameter corresponding to 50% of the volume accumulation in the volume-based particle size distribution (d 50). The volume-based particle size distribution can be measured by a laser diffraction measuring apparatus or an image analyzing apparatus.

In the case where the solid electrolyte material of embodiment 1 is in the form of particles (for example, spheres), the median particle diameter of the solid electrolyte material may be smaller than that of the active material. Thus, the solid electrolyte material and the active material of embodiment 1 can be formed in a good dispersion state.

The solid electrolyte material of embodiment 1 can be produced by the following method.

The raw powder is prepared in a manner to have a target composition. Examples of the raw material powder are an oxide, a hydroxide, a halide or an acid halide (acid halide).

For example, in the case where the solid electrolyte material composed of Li, Ta, O and Cl has the values of the molar ratio Li/M and the molar ratio O/X of 1.0 and 0.2, respectively, at the time of mixing the raw materials, Li is added₂O₂And TaCl₅The preparation was carried out at a molar ratio of 1: 2. Tong (Chinese character of 'tong')The kind of the element of M and X is determined by selecting the kind of the raw powder. The molar ratios of Li/M and O/X are determined by selecting the mixing ratio of the raw material powders.

The reaction product is obtained by subjecting a mixture of raw material powders to a mechanochemical reaction with each other in a mixing device such as a planetary ball mill (i.e., by a mechanochemical grinding method). The reactants may be fired in vacuum or in an inert atmosphere (e.g., an argon atmosphere or a nitrogen atmosphere). Alternatively, the mixture may be fired in vacuum or in an inert gas atmosphere to obtain a reactant. By these methods, the solid electrolyte material of embodiment 1 is obtained.

By the above firing, part of M or part of X may be evaporated. As a result, the values of the molar ratio Li/M and the molar ratio O/X of the obtained solid electrolyte material are larger than those calculated from the molar amount of the raw material powder to be prepared. Specifically, the molar ratio Li/M is about 20% larger, and the molar ratio O/X is about 40% to 75% larger.

The solid electrolyte material of embodiment 1 can be made to have a target diffraction peak position (i.e., crystal structure) by selecting the raw material powder, the mixing ratio of the raw material powder, and the reaction conditions.

The composition of the solid electrolyte material can be determined by, for example, ICP emission spectrometry, ion chromatography, inert gas melting-infrared absorption method, or EPMA (Electron Probe Micro Analyzer; Electron Probe microscopy). However, since the accuracy of measuring the oxygen amount is low, an error of about 10% may be included.

(embodiment 2)

Hereinafter, embodiment 2 will be described. The matters described in embodiment 1 are appropriately omitted.

The battery of embodiment 2 includes a positive electrode, a negative electrode, and an electrolyte layer. The electrolyte layer is disposed between the positive electrode and the negative electrode. At least one selected from the group consisting of a positive electrode, a negative electrode and an electrolyte layer contains the solid electrolyte material of embodiment 1. The battery of embodiment 2 has excellent charge and discharge characteristics.

Fig. 1 shows a cross-sectional view of a battery 1000 according to embodiment 2.

The battery 1000 includes a positive electrode 201, a negative electrode 203, and an electrolyte layer 202. The electrolyte layer 202 is disposed between the positive electrode 201 and the negative electrode 203.

The positive electrode 201 includes positive electrode active material particles 204 and solid electrolyte particles 100.

The electrolyte layer 202 contains an electrolyte material (e.g., a solid electrolyte material).

The negative electrode 203 contains negative electrode active material particles 205 and solid electrolyte particles 100.

The solid electrolyte particles 100 are particles containing the solid electrolyte material of embodiment 1. The solid electrolyte particles 100 may be particles containing a solid electrolyte material as a main component. The particles containing the solid electrolyte material of embodiment 1 as a main component refer to particles containing the solid electrolyte material of embodiment 1 as the largest component. The solid electrolyte particles 100 may be particles made of the solid electrolyte material according to embodiment 1.

The positive electrode 201 contains a material capable of occluding and releasing metal ions (e.g., lithium ions). The positive electrode 201 contains, for example, a positive electrode active material (for example, positive electrode active material particles 204).

Examples of the positive electrode active material are lithium-containing transition metal oxides, transition metal fluorides, polyanionic materials, fluorinated polyanionic materials, transition metal sulfides, transition metal oxysulfides, or transition metal oxynitrides. Examples of lithium-containing transition metal oxides are Li (NiCoAl) O₂、Li(NiCoMn)O₂Or LiCoO₂。

From the viewpoint of cost and safety of the battery, lithium phosphate may be used as the positive electrode active material.

When the positive electrode 201 contains the solid electrolyte material of embodiment 1 and X contains I (i.e., iodine), lithium iron phosphate can be used as the positive electrode active material. The solid electrolyte material of embodiment 1 containing I is easily oxidized. If lithium iron phosphate is used as the positive electrode active material, the oxidation reaction of the solid electrolyte material is suppressed. That is, formation of an oxide layer having low lithium ion conductivity can be suppressed. As a result, the battery has high charge and discharge efficiency.

The positive electrode 201 may contain not only the solid electrolyte material of embodiment 1 but also a transition metal oxyfluoride as a positive electrode active material. The solid electrolyte material according to embodiment 1 is difficult to form a resistive layer even if fluorinated with a transition metal oxyfluoride. As a result, the battery has high charge and discharge efficiency.

The transition metal oxyfluoride contains oxygen and fluorine. As an example, the transition metal oxyfluoride may be represented by the composition formula Li_pMe_qO_mF_nThe compound shown in the specification. Wherein Me is at least one element selected from the group consisting of Mn, Co, Ni, Fe, Al, Cu, V, Nb, Mo, Ti, Cr, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ag, Ru, W, B, Si and P, and satisfies the following formula: p is more than or equal to 0.5 and less than or equal to 1.5, q is more than or equal to 0.5 and less than or equal to 1.0, m is more than or equal to 1 and less than or equal to 2, and n is more than 0 and less than or equal to 1. An example of such a transition metal oxyfluoride is Li_1.05(Ni_0.35Co_0.35Mn_0.3)_0.95O_1.9F_0.1。

The median diameter of the positive electrode active material particles 204 may be 0.1 μm or more and 100 μm or less. When the median diameter of the positive electrode active material particles 204 is 0.1 μm or more, the positive electrode active material particles 204 and the solid electrolyte particles 100 can be formed in a good dispersion state in the positive electrode 201. This improves the charge/discharge characteristics of the battery. When the median diameter of the positive electrode active material particles 204 is 100 μm or less, the lithium diffusion rate in the positive electrode active material particles 204 increases. Therefore, the battery can operate with high output.

The median particle diameter of the positive electrode active material particles 204 may be larger than the solid electrolyte particles 100. This enables the positive electrode active material particles 204 and the solid electrolyte particles 100 to be in a good dispersion state.

In the positive electrode 201, the ratio of the volume of the positive electrode active material particles 204 to the total of the volume of the positive electrode active material particles 204 and the volume of the solid electrolyte particles 100 may be 0.30 or more and 0.95 or less from the viewpoint of the energy density and the output of the battery.

Fig. 2 shows a cross-sectional view of an electrode material 1100 according to embodiment 2. The electrode material 1100 is contained in the positive electrode 201, for example. In order to prevent the electrode active material 206 from reacting with the solid electrolyte particles 100, a coating layer 216 may be formed on the surface of the electrode active material particles 206. This can suppress an increase in the reaction overvoltage of the battery. Examples of the coating material contained in the coating layer 216 include a sulfide solid electrolyte, an oxide solid electrolyte, or a halide solid electrolyte.

In the case where the solid electrolyte particles 100 are sulfide solid electrolytes, the coating material may be the solid electrolyte material of embodiment 1, and X is at least one element selected from Cl and Br. Such a solid electrolyte material of embodiment 1 is less likely to be oxidized than a sulfide solid electrolyte. As a result, the reaction overvoltage of the battery can be suppressed from rising.

In the case where the solid electrolyte particle 100 is the solid electrolyte material of embodiment 1, and X contains I, the coating material may be the solid electrolyte material of embodiment 1, and X is at least one element selected from Cl and Br. The solid electrolyte material of embodiment 1 not containing I is less likely to be oxidized than the solid electrolyte material of embodiment 1 containing I. Therefore, the battery has high charge-discharge efficiency.

In the case where the solid electrolyte particles 100 are the solid electrolyte material of embodiment 1, and X contains I, the coating material may contain an oxide solid electrolyte. The oxide solid electrolyte may be lithium niobate having excellent stability even at a high potential.

The positive electrode 201 may be composed of a 1 st positive electrode layer containing a 1 st positive electrode active material and a 2 nd positive electrode layer containing a 2 nd positive electrode active material. Here, the 2 nd positive electrode layer is disposed between the 1 st positive electrode layer and the electrolyte layer 202, the 1 st positive electrode layer and the 2 nd positive electrode layer contain the solid electrolyte material of embodiment 1 including I, and the coating layer 216 is formed on the surface of the 2 nd positive electrode active material. With the above technical configuration, the solid electrolyte material of embodiment 1 contained in the electrolyte layer 202 can be inhibited from being oxidized by the 2 nd positive electrode active material. As a result, the battery has a high charge capacity. Examples of the coating material contained in the coating layer 206 include a sulfide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, and a halide solid electrolyte. However, when the coating material is a halide solid electrolyte, I is not contained as a halogen element. The 1 st positive electrode active material may be the same material as the 2 nd positive electrode active material, or may be a material different from the 2 nd positive electrode active material.

The thickness of the positive electrode 201 may be 10 μm or more and 500 μm or less from the viewpoint of energy density and output of the battery.

The electrolyte layer 202 contains an electrolyte material. The electrolyte material is, for example, a solid electrolyte material. The electrolyte layer 202 may be a solid electrolyte layer. The solid electrolyte material contained in the electrolyte layer 202 may contain the solid electrolyte material of embodiment 1. The solid electrolyte material contained in the electrolyte layer 202 may be composed of only the solid electrolyte material of embodiment 1.

The solid electrolyte material contained in the electrolyte layer 202 may be composed of only a solid electrolyte material different from the solid electrolyte material of embodiment 1. An example of a solid electrolyte material different from that of embodiment 1 is Li₂MgX’₄、Li₂FeX’₄、Li(Al,Ga,In)X’₄、Li₃(Al,Ga,In)X’₆Or LiI. Wherein X' is at least one element selected from F, Cl, Br and I.

Hereinafter, the solid electrolyte material of embodiment 1 is also referred to as a 1 st solid electrolyte material. A solid electrolyte material different from the solid electrolyte material of embodiment 1 is also referred to as a 2 nd solid electrolyte material.

The electrolyte layer 202 may contain not only the 1 st solid electrolyte material but also the 2 nd solid electrolyte material. The 1 st solid electrolyte material and the 2 nd solid electrolyte material may be uniformly dispersed.

The thickness of the electrolyte layer 202 may be 1 μm or more and 100 μm or less. When the thickness of the electrolyte layer 202 is 1 μm or more, the positive electrode 201 and the negative electrode 203 are less likely to be short-circuited. When the thickness of the electrolyte layer 202 is 100 μm or less, the battery can operate at high output.

The anode 203 contains a material capable of occluding and releasing metal ions (e.g., lithium ions). The negative electrode 203 contains, for example, a negative electrode active material (for example, negative electrode active material particles 205).

Examples of the negative electrode active material include a metal material, a carbon material, an oxide, a nitride, a tin compound, or a silicon compound. The metal material may be a simple metal or an alloy. Examples of the metallic material are lithium metal or lithium alloy. Examples of carbon materials are natural graphite, coke, carbon in graphitized carbon, carbon fibers, spherical carbon, artificial graphite or amorphous carbon. Preferable examples of the negative electrode active material include silicon (i.e., Si), tin (i.e., Sn), a silicon compound, and a tin compound from the viewpoint of capacity density.

The negative electrode active material may be selected according to the reduction resistance of the solid electrolyte material contained in the negative electrode 203. In the case where the negative electrode 203 contains the solid electrolyte material according to embodiment 1, a material capable of occluding and releasing lithium ions at 0.27V or more with respect to lithium can be used as the negative electrode active material. If the anode active material is such a material, the solid electrolyte material of embodiment 1 contained in the anode 203 can be suppressed from being reduced. As a result, the battery has high charge and discharge efficiency. Examples of such materials are titanium oxide, indium metal or lithium alloys. An example of titanium oxide is Li₄Ti₅O₁₂、LiTi₂O₄Or TiO₂。

The median diameter of the negative electrode active material particles 205 is 0.1 μm or more and 100 μm or less. When the median diameter of the negative electrode active material particles 205 is 0.1 μm or more, the negative electrode active material particles 205 and the solid electrolyte particles 100 can be formed in a good dispersion state in the negative electrode 203. This improves the charge/discharge characteristics of the battery. When the median diameter of the negative electrode active material particles 205 is 100 μm or less, the lithium diffusion rate in the negative electrode active material particles 205 increases. Thereby, the battery can operate with high output.

The median particle diameter of the anode active material particles 205 may be larger than that of the solid electrolyte particles 100. This enables the negative electrode active material particles 205 and the solid electrolyte particles 100 to be in a good dispersion state.

In the negative electrode 203, the ratio of the volume of the negative electrode active material particles 205 to the total of the volume of the negative electrode active material particles 205 and the volume of the solid electrolyte particles 100 may be 0.30 or more and 0.95 or less from the viewpoint of the energy density and output of the battery.

The electrode material 1100 shown in fig. 2 may be included in the negative electrode 202. In order to prevent the solid electrolyte particles 100 from reacting with the negative electrode active material (i.e., the electrode active material particles 206), a coating layer 216 may be formed on the surface of the electrode active material particles 206. Thus, the battery has high charge and discharge efficiency. Examples of the coating material contained in the coating layer 216 include a sulfide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, and a halide solid electrolyte.

In the case where the solid electrolyte particle 100 is the solid electrolyte material of embodiment 1, the coating material may be a sulfide solid electrolyte, an oxide solid electrolyte, or a polymer solid electrolyte. An example of a sulfide solid electrolyte is Li₂S-P₂S₅. An example of an oxide solid electrolyte is tri-lithium phosphate. An example of the polymer solid electrolyte is a composite compound of polyethylene oxide and a lithium salt. An example of such a polymer solid electrolyte is lithium bis (trifluoromethanesulfonyl) imide.

The thickness of the negative electrode 203 may be 10 μm or more and 500 μm or less from the viewpoint of energy density and output of the battery.

At least one selected from the cathode 201, the electrolyte layer 202, and the anode 203 may contain a 2 nd solid electrolyte material for the purpose of improving ion conductivity. Examples of the 2 nd solid electrolyte material are a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, or an organic polymer solid electrolyte.

In the present disclosure, "sulfide solid electrolyte" refers to a sulfur-containing solid electrolyte. The "oxide solid electrolyte" refers to a solid electrolyte containing oxygen. The oxide solid electrolyte may contain anions other than oxygen (other than sulfur anions and halogen anions). The "halide solid electrolyte" refers to a solid electrolyte containing a halogen element and containing no sulfur. The halide solid electrolyte may contain not only a halogen element but also oxygen.

An example of a sulfide solid electrolyte is Li₂S-P₂S₅、Li₂S-SiS₂、Li₂S-B₂S₃、Li₂S-GeS₂、Li_3.25Ge_0.25P_0.75S₄Or Li₁₀GeP₂S₁₂。

Examples of oxide solid electrolytes are:

(i) with LiTi₂(PO₄)₃And an NASICON type solid electrolyte represented by a substituted element thereof,

(ii)(LaLi)TiO₃a perovskite-type solid electrolyte of the series,

(iii) with Li₁₄ZnGe₄O₁₆、Li₄SiO₄、LiGeO₄And an element substitution body thereof as a representative LISICON-type solid electrolyte,

(iv) with Li₇La₃Zr₂O₁₂And a substitution product of an element thereof, or

(v)Li₃PO₄And N-substituted forms thereof.

An example of a halide solid electrolyte material is Li_aMe’_bY_cZ₆The compound shown in the specification. Wherein, satisfy the following equation: a + mb +3c is 6 and c > 0. Me' is at least one selected from metallic elements and semimetallic elements other than Li and Y. Z is at least one element selected from F, Cl, Br and I. The value of m represents the valence of Me'.

"half-metal elements" are B, Si, Ge, As, Sb and Te.

The "metal element" is all elements contained in groups 1 to 12 of the periodic table (except hydrogen) and all elements contained in groups 13 to 16 of the periodic table (except B, Si, Ge, As, Sb, Te, C, N, P, O, S and Se).

Me' may be at least one element selected from Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta and Nb.

An example of a halide solid electrolyte is Li₃YCl₆Or Li₃YBr₆。

In the case where the electrolyte layer 202 contains the solid electrolyte material of embodiment 1, the anode 203 may contain a sulfide solid electrolyte material. Thereby, the solid electrolyte material and the anode active material of embodiment 1 are inhibited from contacting each other with respect to the sulfide solid electrolyte material in which the anode active material is electrochemically stable. As a result, the internal resistance of the battery decreases.

Examples of the organic polymer solid electrolyte material include a high molecular compound and a lithium salt compound. The polymer compound may have an ethylene oxide structure. The polymer compound having an ethylene oxide structure can contain a large amount of lithium salt, and thus has higher ionic conductivity.

An example of the lithium salt is LiPF₆、LiBF₄、LiSbF₆、LiAsF₆、LiSO₃CF₃、LiN(SO₂CF₃)₂、LiN(SO₂C₂F₅)₂、LiN(SO₂CF₃)(SO₂C₄F₉) Or LiC (SO)₂CF₃)₃. A lithium salt selected from these may be used alone. Alternatively, a mixture of two or more lithium salts selected from these may also be used.

At least one selected from the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may contain a nonaqueous electrolyte solution, a gel electrolyte, or an ionic liquid for the purpose of facilitating the transfer of lithium ions and improving the output characteristics of the battery.

The nonaqueous electrolytic solution contains a nonaqueous solvent and a lithium salt dissolved in the nonaqueous solvent. Examples of the nonaqueous solvent include a cyclic carbonate solvent, a chain carbonate solvent, a cyclic ether solvent, a chain ether solvent, a cyclic ester solvent, a chain ester solvent, or a fluorine solvent. Examples of the cyclic carbonate solvent are ethylene carbonate, propylene carbonate or butylene carbonate. Examples of the chain carbonate solvent are dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate. Examples of cyclic ether solvents are tetrahydrofuran, 1, 4-dioxane or 1, 3-dioxolane. Examples of the chain ether solvent are 1, 2-dimethoxyethane or 1, 2-diethoxyethane. An example of a cyclic ester solvent is gamma-butyrolactone. An example of the chain ester solvent is methyl acetate. Examples of fluorosolvents are fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate or dimethyl fluorocarbonate. A nonaqueous solvent selected from these may be used alone. Alternatively, a mixture of two or more nonaqueous solvents selected from these may also be used.

An example of the lithium salt is LiPF₆、LiBF₄、LiSbF₆、LiAsF₆、LiSO₃CF₃、LiN(SO₂CF₃)₂、LiN(SO₂C₂F₅)₂、LiN(SO₂CF₃)(SO₂C₄F₉) Or LiC (SO)₂CF₃)₃. A lithium salt selected from these may be used alone. Alternatively, a mixture of two or more lithium salts selected from these may also be used. The concentration of the lithium salt is, for example, in the range of 0.5 mol/liter or more and 2 mol/liter or less.

As the gel electrolyte, a polymer material impregnated with a nonaqueous electrolytic solution can be used. Examples of polymeric materials are polyoxyethylene, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or polymers with ethylene oxide groups.

Examples of cations contained in ionic liquids are:

(i) aliphatic linear quaternary salts such as tetraalkyl amines or tetraalkyl phosphonium,

(ii) aliphatic cyclic ammonium such as pyrrolidinium, morpholinium, imidazolinium, tetrahydropyrimidinium, piperazinium or piperidinium, or

(iii) Nitrogen-containing heterocyclic aromatic cations such as pyridinium or imidazolium.

Of anions contained in ionic liquidsExamples are PF₆ ^-、BF₄ ^-、SbF₆ ^-、AsF₆ ^-、SO₃CF₃ ^-、N(SO₂CF₃)₂ ^-、N(SO₂C₂F₅)₂ ^-、N(SO₂CF₃)(SO₂C₄F₉)^-Or C (SO)₂CF₃)₃ ^-。

The ionic liquid may contain a lithium salt.

At least one selected from the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may contain a binder for the purpose of improving the adhesion between particles.

Examples of binders are polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resins, polyamides, polyimides, polyamideimides, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexamethylene acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexamethylene methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropropylene, styrene-butadiene rubber or carboxymethylcellulose. As the binder, a copolymer may also be used. Examples of the binder include copolymers of two or more materials selected from the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene. Mixtures of two or more selected from the above materials may also be used.

At least one selected from the positive electrode 201 and the negative electrode 203 may contain a conductive assistant for the purpose of improving electron conductivity.

Examples of the conductive assistant are:

(i) graphites such as natural graphites and artificial graphites,

(ii) carbon blacks such as acetylene black and ketjen black,

(iii) conductive fibers such as carbon fibers or metal fibers,

(iv) the carbon fluoride is used as a raw material,

(v) the class of metal powders such as aluminum and the like,

(vi) conductive whiskers such as zinc oxide and potassium titanate,

(vii) a conductive metal oxide such as titanium oxide, or

(viii) And a conductive polymer compound such as polyaniline, polypyrrole, or polythiophene.

For cost reduction, the conductive auxiliary agent (i) or (ii) may be used.

Examples of the shape of the battery according to embodiment 2 include a coin shape, a cylindrical shape, a square shape, a sheet shape, a button shape, a flat shape, and a laminated shape.

(examples)

Hereinafter, the present disclosure will be described in more detail with reference to examples.

(sample 1)

[ production of solid electrolyte Material ]

In a dry atmosphere having a dew point of-30 ℃ or lower (hereinafter referred to as "dry atmosphere"), 1:2 Li is used as a raw material powder₂O₂:TaCl₅Molar ratio prepared Li₂O₂And TaCl₅. These raw material powders were pulverized and mixed in a mortar to obtain a mixed powder. The resultant mixed powder was ground by a planetary ball mill at 600rpm for 24 hours. Then, the mixed powder was fired at 200 ℃ for 6 hours. Thus, a powder of the solid electrolyte material of sample 1 containing a crystal phase composed of Li, Ta, O and Cl was obtained.

The Li content and Ta content of the solid electrolyte material of sample 1 were measured by high-frequency inductively coupled plasma emission spectrometry using a high-frequency inductively coupled plasma emission spectrometer (iCAP 7400, manufactured by Thermo Fisher Scientific). The Cl content of the solid electrolyte material of sample 1 was measured by ion chromatography using an ion chromatography apparatus (available from Dionex, ICS-2000). The O content of the solid electrolyte material of sample 1 was measured by an inert gas melting-infrared absorption method using an oxygen analyzer (EMGA-930, manufactured by horiba ltd.). As a result, in the solid electrolyte material of sample 1, the molar ratio Li/Ta was 1.20 and the molar ratio O/Cl was 0.35.

[ evaluation of ion conductivity ]

Fig. 3 shows a schematic view of a pressure forming die 300 for evaluating the ion conductivity of a solid electrolyte material.

The press mold 300 includes a frame 301, a punch lower portion 302, and a punch upper portion 303. The frame 301 is made of insulating polycarbonate. Punch upper 303 and punch lower 302 are both formed of an electronically conductive stainless steel.

The ion conductivity of the solid electrolyte material of sample 1 was measured by the following method using a press mold 300 shown in fig. 3.

In a dry atmosphere, the powder of the solid electrolyte material of sample 1 (i.e., in fig. 3, the powder 401 of the solid electrolyte material) is filled into the inside of the pressure-forming die 300. Inside the pressure molding die 300, a pressure of 300MPa is applied to the solid electrolyte material of sample 1 using a punch lower portion 302 and a punch upper portion 303. Thus, an ion conductivity measuring cell of sample 1 was obtained.

The punch lower portion 302 and the punch upper portion 303 are connected to a potentiostat (princetonestablished Research, VersaSTAT4) equipped with a frequency response analyzer in a state where pressure is applied. The punch upper portion 303 is connected to the working electrode and the potential measuring terminal. The punch lower portion 302 is connected to the counter electrode and the reference electrode. The ionic conductivity of the solid electrolyte material of sample 1 was measured at room temperature by electrochemical impedance measurement. As a result, the ionic conductivity measured at 22 ℃ was 8.2 mS/cm.

[ evaluation of temperature dependence of ion conductivity ]

Fig. 4 is a graph showing the temperature dependence of the ion conductivity of the solid electrolyte material of sample 1. The results shown in FIG. 4 were measured by the following method.

The ion conductivity measuring unit of sample 1 was placed in a thermostatic bath. The ionic conductivity was measured in both the temperature-increasing and temperature-decreasing processes in the range of-30 ℃ to 80 ℃.

As shown in fig. 4, the solid electrolyte material of sample 1 maintained high lithium ion conductivity in the range of-30 ℃ to 80 ℃.

[ X-ray diffraction ]

Fig. 5 is a graph showing an X-ray diffraction pattern of the solid electrolyte material of sample 1. The results shown in FIG. 5 were measured by the following method.

The X-ray diffraction pattern of the solid electrolyte material of sample 1 was measured using an X-ray diffraction apparatus (RIGAKU, MiniFlex600) in a dry atmosphere having a dew point of-45 ℃. Cu-Kalpha radiation (wavelength: X) was used as the X-ray sourceAnd)。

the solid electrolyte material of sample 1 has a diffraction peak at 11.08 ° (i.e., 1 st range). This result means that the solid electrolyte material of sample 1 contains a crystal phase having high lithium ion conductivity (i.e., the 1 st crystal phase). The solid electrolyte material of sample 1 also had a diffraction peak at 17.92 ° (i.e., 2 nd range).

The solid electrolyte material of sample 1 also has a diffraction peak derived from LiCl. This means that the solid electrolyte material of sample 1 contains the 2 nd crystal phase different from the 1 st crystal phase.

[ production of Battery ]

The solid electrolyte material of sample 1 and LiCoO as a positive electrode active material were mixed in an argon atmosphere having a dew point of-60 ℃ or lower₂Preparation was performed at a volume ratio of 50: 50. These materials were mixed in a mortar to obtain a mixture.

The solid electrolyte material (100mg) of sample 1 and the mixture (10.6mg) were stacked in this order in an insulating cylinder having an inner diameter of 9.5mm to obtain a stacked body. A pressure of 360MPa was applied to the laminate to form a solid electrolyte layer and a positive electrode. The thickness of the solid electrolyte layer was 500 μm.

Subsequently, a Li-In alloy having a thickness of 200 μm was laminated on the solid electrolyte layer to obtain a laminate. A pressure of 80MPa was applied to the laminate to form a negative electrode.

Current collectors formed of stainless steel are attached to the positive and negative electrodes, and current collecting leads are attached to the current collectors.

Finally, the inside of the insulating cylinder is isolated from the outside atmosphere by an insulating sleeve, and the inside of the cylinder is sealed.

Thus, a battery of sample 1 was obtained.

[ Charge/discharge test ]

Fig. 7 is a graph showing the initial discharge characteristics of the battery of sample 1. The results shown in FIG. 7 were measured by the following method.

The cell of sample 1 was placed in a thermostatic bath at 25 ℃.

At 80. mu.A/cm²Until a voltage of 3.6V was reached, the battery of sample 1 was charged with the current density of (d). This current density corresponds to a 0.05C rate. Then, the concentration was adjusted to 80. mu.A/cm²Until a voltage of 2.5V is reached, the cell of sample 1 is discharged. This current density corresponds to a 0.05C rate.

As a result of the charge and discharge test, the battery of sample 1 had an initial discharge capacity of 0.56 mAh.

(sample 2)

As the raw material powder, 0.9:2 Li was used₂O₂:TaCl₅Molar ratio prepared Li₂O₂And TaCl₅. Except for this, a solid electrolyte material of sample 2 was obtained in the same manner as in sample 1. In the solid electrolyte material of sample 2, the molar ratio Li/Ta was 1.08 and the molar ratio O/Cl was 0.31.

The ion conductivity of the solid electrolyte material of sample 2 was measured in the same manner as in sample 1. As a result, the ionic conductivity measured at 22 ℃ was 9.0 mS/cm.

The X-ray diffraction pattern of the solid electrolyte material of sample 2 was measured in the same manner as in sample 1. The measurement results are shown in FIG. 6. The solid electrolyte material of sample 2 has diffraction peaks at 11.06 ° (i.e., 1 st range) and 17.88 ° (i.e., 2 nd range). In addition, the solid electrolyte material of sample 2 also has a diffraction peak derived from LiCl. Therefore, the solid electrolyte material of sample 2 contains the 1 st crystal phase and the 2 nd crystal phase.

(sample 3)

As the raw material powder, 0.8:2 Li was used₂O₂:TaCl₅Molar ratio prepared Li₂O₂And TaCl₅. Except for this, a solid electrolyte material of sample 3 was obtained in the same manner as sample 1. In the solid electrolyte material of sample 3, the molar ratio Li/Ta was 0.96 and the molar ratio O/Cl was 0.27.

The ion conductivity of the solid electrolyte material of sample 3 was measured in the same manner as in sample 1. As a result, the ionic conductivity measured at 22 ℃ was 6.5 mS/cm.

The X-ray diffraction pattern of the solid electrolyte material of sample 3 was measured in the same manner as in sample 1. The measurement results are shown in FIG. 6. The solid electrolyte material of sample 3 has diffraction peaks at 11.09 ° (i.e., 1 st range) and 17.96 ° (i.e., 2 nd range). The solid electrolyte material of sample 3 also has a diffraction peak derived from LiCl. Therefore, the solid electrolyte material of sample 3 contains the 1 st crystal phase and the 2 nd crystal phase.

(sample 4)

As the raw material powder, 0.5:2 Li was used₂O₂:TaCl₅Molar ratio prepared Li₂O₂And TaCl₅. Except for this, a solid electrolyte material of sample 4 was obtained in the same manner as in sample 1. In the solid electrolyte material of sample 4, the molar ratio Li/Ta was 0.60 and the molar ratio O/Cl was 0.16.

The ion conductivity of the solid electrolyte material of sample 4 was measured in the same manner as in sample 1. As a result, the ionic conductivity measured at 22 ℃ was 4.9 mS/cm.

The X-ray diffraction pattern of the solid electrolyte material of sample 4 was measured in the same manner as in sample 1. The measurement results are shown in FIG. 6. The solid electrolyte material of sample 4 has diffraction peaks at 11.08 ° (i.e., 1 st range) and 17.93 ° (i.e., 2 nd range). The solid electrolyte material of sample 4 also has a diffraction peak derived from LiCl. Therefore, the solid electrolyte material of sample 4 contains the 1 st crystal phase and the 2 nd crystal phase.

(sample 5)

As the raw material powder, 1:1 Li was used₂O:TaCl₅Molar ratio prepared Li₂O and TaCl₅. Except for this, a solid electrolyte material of sample 5 was obtained in the same manner as sample 1. In the solid electrolyte material of sample 5, the molar ratio Li/Ta was 2.40 and the molar ratio O/Cl was 0.28.

The ion conductivity of the solid electrolyte material of sample 5 was measured in the same manner as in sample 1. As a result, the ionic conductivity measured at 22 ℃ was 3.3 mS/cm.

The X-ray diffraction pattern of sample 5 was measured in the same manner as sample 1. The measurement results are shown in FIG. 6. The solid electrolyte material of sample 5 has diffraction peaks at 11.08 ° (i.e., 1 st range) and 17.92 ° (i.e., 2 nd range). In addition, the solid electrolyte material of sample 5 also has a diffraction peak derived from LiCl. Therefore, the solid electrolyte material of sample 5 contains the 1 st crystal phase and the 2 nd crystal phase.

(sample 6)

As the raw material powder, 1:1.6:0.4 of Li was used₂O₂:TaCl₅:NbCl₅Molar ratio prepared Li₂O₂、TaCl₅And NbCl₅. Except for this, a solid electrolyte material of sample 6 was obtained in the same manner as sample 1. In the solid electrolyte material of sample 6, the molar ratio Li/(Ta + Nb) was 1.20, and the molar ratio O/Cl was 0.35.

The ion conductivity of the solid electrolyte material of sample 6 was measured in the same manner as in sample 1. As a result, the ionic conductivity measured at 22 ℃ was 6.7 mS/cm.

The X-ray diffraction pattern of the solid electrolyte material of sample 6 was measured in the same manner as sample 1. The measurement results are shown in FIG. 6. The solid electrolyte material of sample 6 has diffraction peaks at 11.09 ° (i.e., 1 st range) and 17.93 ° (i.e., 2 nd range). The solid electrolyte material of sample 6 also has a diffraction peak derived from LiCl. Therefore, the solid electrolyte material of sample 6 contains the 1 st crystal phase and the 2 nd crystal phase.

(sample 7)

As the raw material powder, 1:1:1 Li was used₂O₂:TaCl₅:NbCl₅Molar ratio prepared Li₂O₂、TaCl₅And NbCl₅. Except for this, a solid electrolyte material of sample 7 was obtained in the same manner as sample 1. In the solid electrolyte material of sample 7, the molar ratio Li/(Ta + Nb) was 1.20, and the molar ratio O/Cl was 0.35.

The ion conductivity of the solid electrolyte material of sample 7 was measured in the same manner as in sample 1. As a result, the ionic conductivity measured at 22 ℃ was 5.7 mS/cm.

The X-ray diffraction pattern of the solid electrolyte material of sample 7 was measured in the same manner as in sample 1. The measurement results are shown in FIG. 6. The solid electrolyte material of sample 7 has diffraction peaks at 11.07 ° (i.e., 1 st range) and 17.91 ° (i.e., 2 nd range). In addition, the solid electrolyte material of sample 7 also has a diffraction peak derived from LiCl. Therefore, the solid electrolyte material of sample 7 contains the 1 st crystal phase and the 2 nd crystal phase.

(sample 8)

As raw material powder, 1:1 LiCl: TaCl was used₅LiCl and TaCl were prepared in molar ratio₅. Except for this, a solid electrolyte material of sample 8 was obtained in the same manner as sample 1. In the solid electrolyte material of sample 8, the molar ratio Li/Ta was 1.0 and the molar ratio O/Cl was 0. That is, the solid electrolyte material of sample 8 does not contain O (i.e., oxygen).

The ion conductivity of the solid electrolyte material of sample 8 was measured in the same manner as in sample 1. As a result, the ionic conductivity measured at 22 ℃ was 5.6X 10^-4mS/cm。

The X-ray diffraction pattern of the solid electrolyte material of sample 8 was measured in the same manner as in sample 1. The measurement results are shown in FIG. 5. The solid electrolyte material of sample 8 has no diffraction peak in the 1 st and 2 nd ranges. Therefore, the solid electrolyte material of sample 8 does not contain the 1 st crystal phase.

(sample 9)

As the raw material powder, 1:1 LiCl: Li was used₂O₂The molar ratio of LiCl to Li was prepared₂O₂. Except for this, a solid electrolyte material of sample 9 was obtained in the same manner as sample 1. In the solid electrolyte material of sample 9, the molar ratio O/Cl was 0.5. The solid electrolyte material of sample 9 does not contain element M.

The ion conductivity of the solid electrolyte material of sample 9 was measured in the same manner as in sample 1. As a result, the ionic conductivity measured at 22 ℃ was 1.2X 10^-5mS/cm。

The X-ray diffraction pattern of the solid electrolyte material of sample 9 was measured in the same manner as in sample 1. The measurement results are shown in FIG. 5. The solid electrolyte material of sample 9 has no diffraction peak in the 1 st and 2 nd ranges. Therefore, the solid electrolyte material of sample 9 does not contain the 1 st crystal phase.

The constitutional elements, the molar ratios, and the measurement results of samples 1 to 9 are shown in table 1.

[ Table 1]

(examination)

As can be seen from Table 1, the solid electrolyte materials of samples 1 to 7 have 1 × 10-³High ionic conductivity above mS/cm.

As shown in fig. 4, the solid electrolyte material of sample 1 has high lithium ion conductivity in the range of the expected use temperature of the battery.

The cell of sample 1 was charged and discharged at room temperature.

Comparing samples 1 and 6 with sample 7, it is found that the following equation is satisfied: m is more than or equal to 0.8_Ta/(m_Nb+m_Ta) Under the condition of less than or equal to 1.0, the solid electrolyte material has higher ion conductivity. Comparing sample 1 with sample 6, it is found that the following equation is satisfied: m is_Ta/(m_Nb+m_Ta) When the ion conductivity is 1 (that is, when M is Ta), the ion conductivity is further improved.

It is understood that, when the molar ratio Li/M is 0.96 or more and 1.20 or less, the solid electrolyte material has higher ion conductivity as compared with samples 4 and 5 in samples 1,2 and 3.

It is understood that when the molar ratio O/Cl is 0.31 or more and 0.35 or less in samples 1 and 2 as compared with samples 3 to 5, the solid electrolyte material has higher ion conductivity.

As described above, the solid electrolyte material of the present disclosure has high lithium ion conductivity and is therefore suitable for providing a battery having excellent charge and discharge characteristics.

Industrial applicability

The solid electrolyte material of the present disclosure is useful, for example, for an all-solid lithium ion secondary battery.

Description of the reference numerals

100 solid electrolyte plasmid

201 positive electrode

202 electrolyte layer

203 negative electrode

204 positive electrode active material particle

205 negative electrode active material particle

206 electrode active material particle

216 coating layer

300 compression molding die

301 framework

Lower part of 302 punch press

303 upper part of punch press

401 powder of solid electrolyte material

1000 cell

1100 electrode material