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CN-121507082-B - Controllable polymer gel electrolyte and preparation method thereof

CN121507082BCN 121507082 BCN121507082 BCN 121507082BCN-121507082-B

Abstract

The invention discloses a controllable polymer gel electrolyte and a preparation method and application thereof. The controllable polymer gel electrolyte is formed by in-situ polymerization of a controllable polymer gel electrolyte precursor, wherein the controllable polymer gel electrolyte precursor comprises, by weight, 0.8-2.7 parts of a retarder, 5-27 parts of a cationic polymerization monomer, 15-35 parts of lithium salt and 4-8 parts of a lithium salt additive, and the retarder is cyclic ethers or cyclic siloxane compounds containing fluorine atoms in substituents. The gel process can be controlled by regulating and controlling the proportion of the retarder to the monomer, so that the electrolyte can be kept in a liquid state at room temperature to facilitate storage and infiltration, and a gel structure is formed in situ at the high-temperature aging stage after the battery is assembled. The controllable polymer gel electrolyte is suitable for lithium ion batteries, and can remarkably improve the safety, the cycling stability and the interface compatibility of the batteries.

Inventors

  • ZHU XINGBAO
  • ZHOU YA
  • FU CHUNYAN
  • LI XIAOLONG
  • ZHANG WENQIANG

Assignees

  • 合肥国轩高科动力能源有限公司

Dates

Publication Date
20260508
Application Date
20260112

Claims (8)

  1. 1. The controllable polymer gel electrolyte is characterized by being formed by in-situ polymerization of a controllable polymer gel electrolyte precursor, wherein the controllable polymer gel electrolyte precursor comprises, by weight, 0.8-2.7 parts of a retarder, 5-27 parts of a cationic polymer monomer, 15-35 parts of lithium salt and 4-8 parts of a lithium salt additive; the retarder is selected from one or more of 2- (trifluoromethyl) dioxolane, 2-bis (trifluoromethyl) oxirane, 1, 3-bis (trifluoromethyl) cyclohexane, 3- (perfluoro-n-butane) -1, 2-epoxypropane and 1,3, 5-trimethyl-1, 3, 5-tris (3, 3-trifluoropropyl) cyclotrisiloxane; The cationic polymerization monomer is 1, 3-dioxypentacyclic; the mass ratio of the retarder to the cationic polymerization monomer is 1:10-1:15.
  2. 2. The controlled polymer gel electrolyte of claim 1 wherein the lithium salt and the lithium salt additive are each independently selected from one or more of lithium hexafluorophosphate, lithium bis-fluorosulfonyl imide, lithium tetrafluoroborate, lithium bis-oxalato borate, and lithium difluoro-oxalato borate.
  3. 3. The controllable polymerized gel electrolyte according to claim 1, wherein the controllable polymerized gel electrolyte precursor comprises, by weight, 1.0-2.0 parts of retarder, 10-18 parts of cationic polymerized monomer, 15.19-25 parts of lithium salt and 4.16-6 parts of lithium salt additive; the lithium salt is lithium hexafluorophosphate; the lithium salt additive is lithium difluoro oxalate borate.
  4. 4. The controllable polyelectrolyte gel electrolyte according to claim 1, wherein the controllable polyelectrolyte gel electrolyte precursor further comprises an organic solvent; The organic solvent is selected from one or more of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, methyl formate, ethyl acetate, propyl propionate and gamma-butyrolactone.
  5. 5. A lithium ion battery comprising a controlled polymeric gel electrolyte according to any one of claims 1-4.
  6. 6. The lithium ion battery according to claim 5, wherein the lithium ion battery satisfies at least one of the following conditions (1) to (11); (1) The lithium ion battery also comprises a positive pole piece, a negative pole piece and a diaphragm; (2) The positive electrode plate comprises a current collector and a positive electrode material layer coated on the surface of the positive electrode current collector; (3) The positive electrode material layer comprises a positive electrode active material, a conductive agent and a binder; (4) The negative electrode plate comprises a current collector and a negative electrode material layer coated on the surface of the negative electrode current collector; (5) The negative electrode material layer comprises a negative electrode active material, a conductive agent and a binder; (6) The positive electrode active material is selected from one or more of lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium cobalt oxide, lithium manganese iron phosphate and lithium nickel cobalt aluminate; (7) The negative electrode active material is selected from one or more of graphite, metallic lithium alloy, silicon carbon material, tin-based material and silicon oxygen material; (8) The conductive agent is selected from one or more of conductive carbon black, conductive graphite, carbon fiber and carbon nano tube; (9) The binder is selected from one or more of styrene-butadiene rubber, nitrile rubber, polyvinylidene fluoride and polytetrafluoroethylene; (10) The mass ratio of the positive electrode active material to the conductive agent to the binder is (80-95): 2-10): 3-10% (11) The mass ratio of the negative electrode active material to the conductive agent to the binder is (85-95)/(1-6)/(4-9).
  7. 7. A method of making the lithium ion battery of claim 5 or 6, comprising the steps of: S1, dissolving lithium salt and a lithium salt additive in an organic solvent to prepare an electrolyte substrate; s2, adding the retarder and the cationic polymerization monomer into the electrolyte substrate obtained in the step S1, and uniformly mixing to obtain a gel precursor; S3, injecting the gel precursor obtained in the standing step S2 into a battery cell, standing, and sequentially performing formation charging, aging treatment, sealing and capacity division to obtain the lithium ion battery.
  8. 8. The method of claim 7, wherein the method satisfies at least one of the following conditions (12) - (16): (12) The concentration of lithium salt in the step S1 is 1.0 mol/L-2.0 mol/L, and the concentration of lithium salt additive is 0.2 mol/L-0.55 mol/L; (13) The standing temperature in the step S3 is 20-30 ℃, and the standing time is 12-120 hours; (14) The formation charging process in the step S3 is to charge to 3.4V with 0.02C constant current, to 3.6V with 0.1C constant current, and to 3.8V with 0.2C constant current in sequence; (15) The temperature of the aging treatment in the step S3 is 45-60 ℃, and the time of the aging treatment is 48-72 hours; (16) The capacity-dividing process in the step S3 is to charge to 4.25V with constant current and constant voltage of 0.33C, discharge to 2.5V with constant current of 0.05C and discharge for 5 times.

Description

Controllable polymer gel electrolyte and preparation method thereof Technical Field The invention belongs to the technical field of batteries, and particularly relates to a controllable polymer gel electrolyte and a preparation method thereof. Background Semi-solid batteries have become a focus of recent research. In various polymerization modes of the semi-solid gel electrolyte, the photo/thermal initiation polymerization inevitably requires additional addition of an initiator to promote the polymerization reaction, or additional light and high-temperature curing process is added, so that the method cannot be completely matched with the existing battery manufacturing process, and the cationic polymerization can utilize Lewis acid generated by the hydrolysis of lithium salt as an initiator to carry out the polymerization at a relatively low temperature, so that the method has unique application advantages. However, the electrolyte is easy to self-polymerize, difficult to store at room temperature, and incapable of fully infiltrating due to early gelation after liquid injection. The gel monomer of the cationic ring-opening polymerization type can directly take Lewis acid dissociated by lithium salt as an initiator, the initiator is not required to be additionally added, meanwhile, polymerization can be carried out under the condition of relatively low temperature, and an additional high-temperature curing process is avoided, so that the application of the controllable polymerization gel electrolyte is simpler and more convenient, and the process flow of the preparation of the battery cell can be basically consistent with that of a traditional liquid battery cell. However, a hidden trouble is caused by that the gel electrolyte which is too easy to polymerize automatically polymerizes in a short time at room temperature, which is inconvenient for storage and transportation and is unfavorable for the electrolyte to fully infiltrate the battery cell after the electrolyte is injected. Disclosure of Invention The application provides a controllable polymerized gel electrolyte, which is formed by in-situ polymerization of a controllable polymerized gel electrolyte precursor, wherein the controllable polymerized gel electrolyte precursor comprises, by weight, 0.8-2.7 parts of a retarder, 5-27 parts of a cationic polymerization monomer, 15-35 parts of a lithium salt and 4-8 parts of a lithium salt additive; the retarder is a cyclic ether compound or a cyclic siloxane compound containing fluorine atoms in substituents; the mass ratio of the retarder to the cationic polymerization monomer is 1:10-1:15. In some embodiments, the retarder is specifically 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.8, 1.9, 2.0, 2.1, 2.4, 2.5, or 2.7 parts by weight. In some embodiments, the cationic polymerizable monomer is specifically 5, 8, 10, 12, 15, 16.8, 18, 20, 22, 25, or 27 parts by weight. In some embodiments, the lithium salt is specifically 15, 15.19, 18, 19, 20, 25, 28, 30, 32, or 35 parts by weight. In some embodiments, the lithium salt additive is specifically 4, 4.16, 4.5, 5, 5.5, 6, 7, or 8 parts by weight. The controllable polymerized gel electrolyte formula designed by the invention can slow down the self-polymerization process of the gel electrolyte at room temperature by finely configuring the proportion of the monomer to the retarder, and can be normally gelled when reaching higher temperature, thereby realizing controllable gelation process management and being completely suitable for the production process of the existing liquid battery. In some embodiments, the retarder is selected from one or more of 3- (2, 3-tetrafluoropropoxy) -1, 2-propylene oxide, 2- (trifluoromethyl) dioxolane, 2-bis (trifluoromethyl) oxirane, 1, 3-bis (trifluoromethyl) cyclohexane, 3- (perfluoro-n-butane) -1, 2-propylene oxide, 1,3, 5-trimethyl-1, 3, 5-tris (3, 3-trifluoropropyl) cyclotrisiloxane. The retarder used in the application is rich in fluorine, has a strong electron-withdrawing effect, can play a role in increasing the polymerization reaction energy of monomers and slowing down the polymerization speed at room temperature, can assist in forming an advantageous CEI/SEI film rich in fluoride on the surface of an electrode, and improves the high-pressure resistance of the controllable polymer gel electrolyte. The retarder also participates in cationic polymerization reaction, can form a cross-linking structure with cationic polymerization monomers, improves the stability of the controllable polymer gel electrolyte, and does not need to consider the influence of initiator and retarder residues. In some embodiments, the cationically polymerizable monomer is selected from one or more of ethylene oxide, propylene oxide, epichlorohydrin, tetrahydrofuran, 2, 3-dihydrofuran, 1, 3-dioxolane, 1, 3-dioxane, 5-trioxane, maleic anhydride, succinic anhydride, glutaric anhydride, pentaerythritol glycidyl ether, trimethylolpropane triglycidyl ether, tr