A kind of preparation method of high and low temperature resistant lithium ion battery

Abstract

The invention discloses a method for preparing a high and low temperature resistant lithium ion battery. The invention adds a three-arm polyvinyl carbonate additive obtained by cycloaddition reaction of VC, PS and VEC solvents, specifically through high temperature heating and catalyst Under the combined action, the VEC double bond is formed by addition reaction with VC and PS respectively. Since the additive has a VC ring group, a polymerized alkyl lithium carbonate film can be formed on the surface of the graphite negative electrode, effectively avoiding the occurrence of side effects between the electrolyte and the negative electrode. Reaction, as measured by experiments, the internal resistance change rate of the high-low temperature resistant lithium-ion battery stored at 75°C for 48 hours is 19.8‑21.3%, and the discharge capacity retention rate at ‑40°C / 0.2C low temperature is 79.1‑80.5%. The technical problem of high temperature resistance and low temperature resistance of lithium-ion batteries in the technology is not good.

Description

technical field [0001] The invention relates to the technical field of lithium ion battery production, in particular to a preparation method of a high and low temperature resistant lithium ion battery. Background technique [0002] Lithium-ion battery is a secondary battery (rechargeable battery) that mainly relies on the movement of lithium ions between the positive and negative electrodes to work. During the charging and discharging process, Li+ intercalates and deintercalates back and forth between the two electrodes: when charging, Li+ is deintercalated from the positive electrode, intercalated into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; the opposite is true during discharge. [0003] Existing lithium-ion batteries do not have good high-temperature and low-temperature resistance characteristics, which will greatly affect the internal resistance change and capacity retention of lithium-ion batteries in high-t...

AI Technical Summary

Problems solved by technology

[0004] The object of the present invention is to provide a kind of preparation method of high and low temperature resistant lithium ion battery, solve following technical problem: (1) by adding the three-arm polyvinyl carbonate obtained by cycloaddition reaction by VC, PS and VEC solvent Additives are formed through the addition reaction of VEC double bonds with VC and PS under the combined action of high temperature heating and catalysts. Since the additives have VC ring groups, a polymeric alkyl lithium carbonate film can be formed on the surface of the graphite negative electrode. , effectively avoid the side reaction between the electrolyte and the negative electrode; at the same time, the addition reaction of the double bond effectively inhibits the decomposition and co-embedding of PC on the graphite negative electrode, so it can effectively improve the high and low temperature resistance of the battery while improving the battery cycle performance Performance, through the selection of acrylic monomers to improve the cross-linked structure of acrylic adhesive, so that it has good adhesion and electrolyte corrosion resistance, using nanoporous silica to modify acrylic adhesive to improve its Electrolyte corrosion resistance and insulation, and the high specific surface properties of nanoporous silica are conducive to its cross-linking combination with acrylic acid monomers. According to experiments, the high and low temperature resistant lithium-ion battery can be stored at a high temperature of 75 ℃ for 48 hours. The resistance change rate is 19.8-21.3%, and the -40°C / 0.2C low-temperature discharge capacity retention rate is 79.1-80.5%, which solves the technical problems of lithium-ion batteries in the prior art with poor high-temperature resistance and low-temperature resistance; (2) Apply a layer of acrylic adhesive on the top of the shell, put the shell with the acrylic adhesive face up into the lithium battery slot on the lower slot plate, and then drive the motor output shaft to drive the gear to rotate, and the gear meshes with the rack Drive the moving plate to move, the moving plate moves towards the bottom of the top plate along the slide rail on the installation platform through the slider at the bottom, after the lower groove plate moves to the bottom of the top plate, the piston rod of the telescopic cylinder pushes the lifting plate downward, and the lifting plate is connected with the connecting rod through the connecting rod The pin drives the heating template down, and the heating template heats the acrylic adhesive surface on the shell. After the hot pressing is completed, the moving plate drives the lower groove plate to move out from the bottom of the top plate to seal the top of the shell, then turn over the cooling plate, and put the cooling plate The cooling tank on the top is covered above the shell, and the cooling pump cools down the cooling tank through the circulating cooling pipe, and then cools the hot-pressed acrylic adhesive surface, and then completes the top sealing to form a pouch battery without liquid injection, so that The capping device can cool the top of the shell after heat sealing, which facilitates the capping process of the lithium-ion battery, and solves the problem that the capping efficiency of the lithium-ion battery in the prior art is not high, and the shell needs to be automatically cooled or taken to a cooling place after heat sealing. device for cooling

Images