阅读说明：本技术 离子液体与离子液体电解液及其在电池中的应用 (Ionic liquid, ionic liquid electrolyte and application of ionic liquid electrolyte in battery ) 是由 赵春荣 赵金玲 赵尚骞 杨容 弓胜民 常增花 张立 庞静 王建涛 卢世刚 于 2020-06-29 设计创作，主要内容包括：本发明涉及电池技术领域,尤其涉及离子液体与离子液体电解液及其在电池中的应用。所述离子液体的结构式如式I所示：<Image he="360" wi="700" file="DDA0002561087200000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>具有上述结构式的离子液体不易挥发、耐热性高,且化学稳定性高；将该离子液体作为电池的电解液、或者固态电池的添加剂,能够大幅度提高离子传导,同时降低界面阻抗,从而有效提高电池的性能。(The invention relates to the technical field of batteries, in particular to ionic liquid, ionic liquid electrolyte and application of the ionic liquid electrolyte in a battery. The above-mentionedThe structural formula of the ionic liquid is shown as formula I: the ionic liquid with the structural formula is not easy to volatilize, has high heat resistance and high chemical stability; the ionic liquid is used as electrolyte of the battery or additive of the solid battery, so that the ionic conduction can be greatly improved, and the interface impedance is reduced, thereby effectively improving the performance of the battery.)

1. An ionic liquid, wherein the structural formula of the ionic liquid is shown as formula I:

2. the ionic liquid of claim 1, wherein the ionic liquid does not dissolve and react with the solid electrolyte.

3. The ionic liquid of claim 2, wherein the solid electrolyte is one or more of a sulfide solid electrolyte, a halide solid electrolyte and an oxide solid electrolyte.

4. A method for preparing an ionic liquid according to any one of claims 1 to 3, comprising: adding lithium salt into an organic solvent, and stirring at 30-100 ℃ until the lithium salt is completely dissolved;

preferably, the lithium salt is lithium bis (fluorosulfonyl) imide, and the organic solvent is isopropyl ether.

5. The method of claim 4, comprising: adding the lithium bis (fluorosulfonyl) imide into isopropyl ether, and stirring at 60-80 ℃ until the lithium bis (fluorosulfonyl) imide is completely dissolved;

the molar ratio of the lithium bis (fluorosulfonyl) imide to the isopropyl ether is 0.5-1: 0.5 to 1; preferably 1: 1.

6. An ionic liquid electrolyte comprising the ionic liquid according to any one of claims 1 to 3.

7. The ionic liquid electrolyte of claim 6, further comprising an additive; the additive is selected from one or more of a solvent, other ionic liquid and electrolyte;

preferably, the molar ratio of the ionic liquid to the additive is 1: 0.1 to 1.

8. Use of an ionic liquid according to any one of claims 1 to 3 or an ionic liquid electrolyte according to claim 6 or 7 in a battery; preferably, the battery is a lithium ion battery or a lithium battery.

9. A lithium ion battery, comprising: a positive electrode active material layer containing a positive electrode active material, a negative electrode active material layer containing a negative electrode active material, and a solid electrolyte layer formed between the positive electrode active material layer and the negative electrode active material layer;

wherein at least one of the positive electrode active material layer, the negative electrode active material layer and the solid electrolyte layer contains the ionic liquid according to any one of claims 1 to 3 or the ionic liquid electrolyte according to claim 6 or 7.

10. A lithium battery comprising the ionic liquid according to any one of claims 1 to 3 or the ionic liquid electrolyte according to claim 6 or 7.

Technical Field

The invention relates to the technical field of batteries, in particular to ionic liquid, ionic liquid electrolyte and application of the ionic liquid electrolyte in a battery.

Background

Safety is one of the most important issues in the research of lithium ion batteries and lithium batteries, and the safety of an electrolyte solution is most important in terms of battery safety. However, the organic electrolyte adopted by the commercial lithium secondary battery is volatile and flammable, which inevitably brings about safety hazards, so that the development of the solid-state battery is an urgent pursuit in the industry for improving the safety performance of the lithium battery. With the rapid development of solid electrolytes, various types of solid electrolyte materials such as sulfide electrolyte materials, oxide electrolyte materials, halide electrolyte materials, and the like have been developed, wherein halide solid electrolytes are compatible with commercially commonly used oxide positive electrode materials such as LCO, NMC, and the like due to their high ionic conductivity and simple preparation method (angelw.chem.int.ed.2019, 58, 1 to 8), and thus are expected to realize commercial application values of all-solid secondary batteries.

In the current lithium ion battery or lithium battery system, the solid-state battery adopts brand new solid-state electrolyte to replace the current organic electrolyte and diaphragm, has high safety and high volume energy density, has wide adaptability with different novel high specific energy electrode systems (such as a lithium sulfur system, a metal-air system and the like), can further improve the mass energy density, and is expected to become a final solution of the next generation of power batteries.

The technical difficulties of low ionic conductivity, overlarge interface impedance, low cycle frequency and the like of the all-solid-state lithium battery are not critical breakthrough and are difficult to realize rapid industrialization in a short period. At present, the inorganic electrolyte filler reinforced polymer matrix composite Solid electrolyte effectively improves the lithium ion conductivity of the Solid electrolyte and improves the interface resistance between the Solid electrolyte and an electrode material (Nature, 1998, 394, 456; Solid State Ionics, 2009, 180, 1267; Nano Energy, 2016, 28, 447), but still cannot meet the requirement of the commercial development of the Solid lithium ion battery.

The Chinese patent publications CN1050946A, CN10107645013A and CN108365260A all adopt quasi-solid electrolyte to replace all-solid electrolyte, and the quasi-solid electrolyte comprises solid electrolyte and liquid electrolyte containing lithium salt. The invention patents of China with publication numbers CN110120545A, CN109768318A, CN109980290A, CN110048168A and CN110112421A all prepare solid-liquid mixed storage batteries, wherein, the surfaces of the anode and the cathode are both provided with a layer of buffer glue layer, and the glue layer adopts ester solvents such as ethylene oxide PEO, polypropylene carbonate and the like; furthermore, wufeng et al injected ionic liquid into the electrolyte layer to prepare a semi-solid battery, and the performance of the battery was significantly improved (Feng Wu, Chemistry of Materials, 2016). However, these solvents and ionic liquid electrolytes are not stable with halide solid electrolytes.

In summary, the ionic liquid or common electrolyte used in the prior art is liable to react with polar solvent due to chemical instability of sulfide, while the halide solid electrolyte is also liable to react with conventional electrolyte, and a stable solvent with the solid electrolyte needs to be found to prepare a new electrolyte. Since an ionic liquid electrolyte that is liquid at room temperature has non-volatility, high heat resistance, a wide liquid temperature range, non-flammability, and high chemical stability, ionic liquids have attracted attention as "green liquids" in recent years, and research on ionic liquids as lithium battery electrolytes has attracted extensive interest in academia and great expectations in the industry.

In view of this, the invention is particularly proposed.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides ionic liquid, ionic liquid electrolyte and application thereof in a battery.

As a first object of the present invention, there is provided an ionic liquid; specifically, the structural formula of the ionic liquid is shown as formula I:

in the research and development process, the ionic liquid with the structural formula is unexpectedly found to be difficult to volatilize, high in heat resistance and high in chemical stability; the ionic liquid is used as electrolyte of the battery or additive of the solid battery, so that the ionic conduction can be greatly improved, and the interface impedance is reduced, thereby effectively improving the performance of the battery.

Preferably, the ionic liquid does not dissolve and react with the solid electrolyte.

Further, the solid electrolyte is one or more of a sulfide solid electrolyte, a halide solid electrolyte and an oxide solid electrolyte.

In a specific embodiment, the solid electrolyte is Li₃InCl₆、LiPSCl、Li₁₀GeP₂S₁₂One or more of them.

In the invention, the solid electrolyte is stable in the ionic liquid, and the performance of the solid battery can be effectively improved by using the ionic liquid in the solid battery.

As a second object of the present invention, there is provided a method for producing the above ionic liquid; specifically, the preparation method comprises the following steps: adding lithium salt into an organic solvent, and stirring at 30-100 ℃ until the lithium salt is completely dissolved.

Preferably, the lithium salt is lithium bis (fluorosulfonyl) imide (LiFSI), and the organic solvent is isopropyl ether.

As a preferred technical scheme, the preparation method comprises the following steps: adding the lithium bis (fluorosulfonyl) imide into isopropyl ether, and stirring at 60-80 ℃ until the lithium bis (fluorosulfonyl) imide is completely dissolved;

the molar ratio of the lithium bis (fluorosulfonyl) imide to the isopropyl ether is 0.5-1: 0.5 to 1; preferably 1: 1.

The ionic liquid prepared by the method has better performance.

As a third object of the present invention, there is provided an ionic liquid electrolyte; specifically, the ionic liquid electrolyte comprises the ionic liquid.

Preferably, the ionic liquid electrolyte further comprises an additive; the additive is selected from one or more of a solvent, other ionic liquid and electrolyte.

Further, the molar ratio of the ionic liquid to the additive is 1: 0.1 to 1.

In particular embodiments, the additive is isopropyl ether, Propylene Carbonate (PC), or Li (G4) TFSI.

As a fourth object of the present invention, there is provided the use of the above-mentioned ionic liquid or the above-mentioned ionic liquid electrolyte in a battery;

preferably, the battery is a lithium ion battery or a lithium battery.

As a fifth object of the present invention, there is provided a lithium ion battery; specifically, the lithium ion battery includes: a positive electrode active material layer containing a positive electrode active material, a negative electrode active material layer containing a negative electrode active material, and a solid electrolyte layer formed between the positive electrode active material layer and the negative electrode active material layer;

wherein at least one of the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer contains the ionic liquid or the ionic liquid electrolyte.

As a sixth object of the present invention, there is provided a lithium battery; specifically, the lithium battery comprises the ionic liquid or the ionic liquid electrolyte.

The invention has the beneficial effects that:

the ionic liquid and the ionic liquid electrolyte provided by the invention are not easy to volatilize, have high heat resistance and high chemical stability; the ionic liquid or the ionic liquid electrolyte is used as the electrolyte of the battery or the additive of the solid battery, so that the ionic conduction can be greatly improved, and the interface impedance is reduced, thereby effectively improving the performance of the battery.

Drawings

Fig. 1 is a 0.1C discharge curve for the cells of example 12 and comparative example 1 of the present invention.

Fig. 2 is a discharge curve of the battery 1C of example 13 and comparative example 2 in the present invention.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

Unless otherwise specified, the test reagents and materials used in the examples of the present invention are commercially available.

Unless otherwise specified, the technical means used in the examples of the present invention are conventional means well known to those skilled in the art.