CN-122000446-A - Gel polymer electrolyte, preparation method thereof and battery

CN122000446ACN 122000446 ACN122000446 ACN 122000446ACN-122000446-A

Abstract

The invention discloses a gel polymer electrolyte, a preparation method thereof and a battery. The gel polymer electrolyte comprises a polymer matrix and electrolyte solution positioned in the polymer matrix, wherein the polymer matrix comprises a polymer formed by polymerizing a phosphate compound shown in a formula I: In the formula I, R 1 and R 2 are respectively substituted alkyl or unsubstituted alkyl of C1-C4, wherein the substituent group in the substituted alkyl is selected from at least one of halogen and cyano, the electrolyte comprises a carbonate solvent and an additive, and the additive comprises lithium bis-salicylateborate shown in the formula II: the gel polymer electrolyte comprises a polymer polymerized by phosphate monomers and lithium bis-salicylates borate, so that the oxidation potential of the carbonate electrolyte can be increased, and the battery performance can be improved.

Inventors

CHENG PENGFEI
CHEN XIAOTONG
LIU ZEXUAN
FAN CHAOJUN
FAN WEIZHEN
SHI LITAO

Assignees

广州天赐高新材料股份有限公司

Dates

Publication Date: 20260508
Application Date: 20241106

Claims (11)

1. A gel polymer electrolyte, comprising: a polymer matrix; an electrolyte disposed in the polymer matrix; wherein the polymer matrix comprises a polymer formed by polymerizing a phosphate compound shown in a formula I: in the formula I, R 1 and R 2 are respectively C1-C4 substituted alkyl or C1-C4 unsubstituted alkyl, wherein the substituent in the C1-C4 substituted alkyl is at least one of halogen and cyano; the electrolyte comprises a carbonate solvent and an additive; The additive comprises lithium bis-salicylates borate shown in formula II:
2. The gel polymer electrolyte according to claim 1, wherein R 1 and R 2 are each a C1-C2 substituted alkyl group or a C1-C2 unsubstituted alkyl group, and wherein the substituent in the C1-C2 substituted alkyl group is one selected from halogen and cyano.
3. The gel polymer electrolyte of claim 1, wherein the substituent in the C1-C4 substituted alkyl group is fluorine.
4. A gel polymer electrolyte according to any one of claims 1 to 3, wherein the mass percentage of the polymer matrix in the gel polymer electrolyte is 7% -20%, and the mass percentage of the electrolyte in the gel polymer electrolyte is 80% -93%.
5. The gel polymer electrolyte according to claim 1, wherein the mass percentage of the additive in the electrolyte is 0.05% -5%.
6. The gel polymer electrolyte of claim 1, wherein the carbonate solvent comprises at least one of ethylene carbonate, propylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, bis-fluoroethylene carbonate, dimethyl carbonate, ethylmethyl carbonate, and diethyl carbonate; And/or the electrolyte further comprises a lithium salt, wherein the lithium salt comprises at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide, lithium bis (oxalato) borate, lithium difluoro (oxalato) phosphate, lithium tetrafluorooxalate phosphate and 4, 5-dicyano-2-trifluoromethyl-imidazole lithium.
7. A method for preparing a gel polymer electrolyte, comprising: Mixing raw materials including phosphate compounds shown in a formula I, a cross-linking agent, an initiator and electrolyte to obtain a mixed solution, and carrying out polymerization treatment on the mixed solution to obtain the gel polymer electrolyte according to any one of claims 1 to 6.
8. The method of claim 7, wherein at least one of the following is satisfied: (a) The mass ratio of the phosphate compound shown in the formula I to the cross-linking agent is (85-70) to (15-30); (b) The mass percentage content of the initiator in the total mass of the phosphate compound shown in the formula I and the cross-linking agent is 0.02% -0.1%; (c) The mass percentage of the additive in the electrolyte is 0.05% -5%; (d) The total mass of the electrolyte is that the total mass of the phosphate compound shown in the formula I and the cross-linking agent is = (93-80) = (7-20), and the sum of the front item and the rear item is 100.
9. The method according to claim 7 or 8, wherein, (I) The initiator comprises at least one of azodiisobutyronitrile, dibenzoyl peroxide, diisopropyl peroxydicarbonate and N, N-dimethylaniline; (ii) The cross-linking agent comprises polyethylene glycol dimethacrylate or carboxylic ester compounds, wherein: the molecular formula of the polyethylene glycol dimethacrylate is C 3 H 5 C(O)(OCH 2 CH 2 ) n OC(O)C 3 H 5 , wherein n=1-10; The structure of the carboxylic ester compound is shown in a formula III:
10. The preparation method according to claim 7, wherein the control parameters in the polymerization treatment of the mixed solution include a temperature of 40-80 ℃ and/or a time of 6-24 hours.
11. A battery comprising the gel polymer electrolyte according to any one of claims 1 to 6, or the gel polymer electrolyte obtained by the production method according to any one of claims 7 to 10.

Description

Gel polymer electrolyte, preparation method thereof and battery Technical Field The invention belongs to the technical field of batteries, and particularly relates to a gel polymer electrolyte, a preparation method thereof and a battery. Background Commercial lithium ion battery electrolytes are composed primarily of conductive lithium salts (e.g., liPF 6), linear and cyclic carbonate solvents, and small amounts of functional additives. The electrolyte has high conductivity, good aluminum foil passivation performance and wide electrochemical window, and can form a chemically and electrochemically stable solid electrolyte membrane on the surface of the graphite cathode. However, the liquid electrolyte has risks of liquid leakage, combustion, internal short circuit and the like, has low safety coefficient, and is easy to cause the safety problem of the battery. The gel polymer electrolyte utilizes a polymer network to adsorb liquid electrolyte, can solve potential safety problems such as leakage and combustion and the like of the liquid electrolyte, inherits good matching property between the liquid electrolyte and positive and negative electrode materials, and is a field of important attention in industry and academia in the past three decades. However, the gel polymer electrolyte commonly used at present still faces the problem of low oxidation potential, and the cycle performance of the battery is reduced under a high-voltage working state, so that the market popularization of the gel electrolyte in the 4V-class battery is severely limited. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the related art to some extent. To this end, an object of the present invention is to provide a gel polymer electrolyte, a method of preparing the same, and a battery. The oxidation potential of the gel polymer electrolyte can be increased by the synergistic effect of the polymer polymerized by the phosphate monomer and lithium bis-salicylates borate, and finally the battery performance is improved. In one aspect of the invention, the invention provides a gel polymer electrolyte comprising: a polymer matrix; an electrolyte disposed in the polymer matrix; wherein the polymer matrix comprises a polymer formed by polymerizing a phosphate compound shown in a formula I: In the formula I, R 1 and R 2 are respectively C1-C4 substituted alkyl or C1-C4 unsubstituted alkyl, wherein the substituent in the C1-C4 substituted alkyl is at least one selected from halogen and cyano; the electrolyte comprises a carbonate solvent and an additive; The additive comprises lithium bis-salicylates borate shown in formula II: The gel polymer electrolyte provided by the application comprises a polymer formed by polymerizing a phosphate compound serving as a monomer and a carbonate electrolyte. On one hand, the polymer formed by polymerizing the phosphate monomer has higher oxidation potential and can be matched with a high-voltage positive electrode material, and on the other hand, the lithium bis (salicylate) borate (also called as Lithium Bis (silicate) borate, abbreviated as LiBSB) has good film forming capability, so that the polymer can be oxidized and decomposed on the surface of an electrode to form a high-quality and high-voltage-resistant excellent interface film, and the oxidation potential of a carbonate electrolyte is improved. Finally, the oxidation potential of the gel polymer electrolyte can be increased through the synergistic effect of the polymer formed by the polymerization of the phosphate monomer and LiBSB, and finally the aim of improving the battery performance is achieved. The carboxylate monomer is a common polymerization monomer for preparing gel electrolyte at present, but a polymer formed by polymerization of the carboxylate monomer has the problem of low oxidation potential and has poor matching property with a high-voltage (> 4.25V vs. Li/Li +) positive electrode material. Compared with the carboxylate monomer, the phosphate polymer formed by polymerization of the phosphate monomer has high oxidation potential and good compatibility with the high-voltage positive electrode material. In addition, the phosphate polymer formed after the polymerization of the phosphate monomer can weaken the combustibility of the liquid carbonate electrolyte, greatly improve the thermal stability of the gel electrolyte, reduce the thermal runaway risk of the battery and further improve the safety of the battery. Taking the traditional LiPF 6 carbonate electrolyte as an example, the oxidation potential of the electrolyte is low, and when the electrolyte is used in a high-voltage (> 4.25v vs. Li/Li +) battery, the oxidative decomposition of the electrolyte is serious, and the battery performance is rapidly attenuated. LiBSB as an additive, can obviously improve the oxidation potential of the LiPF 6 carbonate electrolyte. This is mainly because LiBSB has excellent film forming ability, and