Local deformation improvement method and battery of high energy density flexible packaging ion battery

Abstract

The invention provides a method for improving local deformation of a high-energy-density soft-packed ion battery and the battery, comprising: setting protective glue parameters and pasting protective glue on positive and negative pole pieces according to the protective glue parameters; using the positive pole piece pasted with protective glue Prepare winding cores with negative electrode sheets, and prepare the winding cores into batteries according to the battery preparation process; use a high-temperature pressurized forming cabinet to perform a formation operation on the batteries, and collect the batteries during the formation operations The thickness of multiple positions, according to the thickness of multiple positions of the battery, adjust the post-forming surface pressure of the battery; calculate the free electrolyte coefficient of the formed battery and set the vacuum according to the free electrolyte coefficient Time, according to the vacuuming time, vacuumize the battery cells that have been formed, and use the vacuumized battery cells to prepare lithium-ion batteries. The invention can obviously reduce the local deformation of the battery and enhance the service performance of the battery.

Description

technical field [0001] The invention belongs to the technical field of lithium batteries, and in particular relates to a method for improving local deformation of a high-energy-density soft-packaged ion battery and the battery. Background technique [0002] With the development of thinner and smarter mobile phones, the energy density of mobile phone batteries is getting higher and higher. In order to improve the energy density of batteries, major battery manufacturers are increasingly using base films with a thickness of Coated diaphragms coated with polymer materials such as polyvinylidene fluoride or acrylic, use graphite materials with a compacted density of 1.9, lithium cobalt oxide materials with a compacted density of 4.2 or even above 4.4, and ultra-thin materials with a thickness of 65um and 76um. At the same time, the coating surface density of the positive and negative pole pieces is getting higher and higher. With the use of these materials and high coating area ...

AI Technical Summary

Problems solved by technology

The reason is that the degree of polymerization of the glue on the diaphragm and the positive electrode sheet after high temperature and pressurization is different, resulting in serious polarization inside the battery.

The second is that the use of high compaction and high coating surface density for the positive and negative electrodes will slow down the wetting speed of the electrolyte on the electrode sheet during the standing process after the liquid injection, and the SEI film formed after the battery has not been fully infiltrated is unstable. Lithium is easily decomposed during the process, resulting in deformation of the lithium decomposed position and rapid battery capacity decay

Third, in the case of high compaction and high coating amount, due to the low porosity of the pole piece and the slow liquid absorption speed, a part of the free electrolyte that has not been sucked into the inside of the pole piece is bound to remain inside the battery after two seals

If there is a lot of free electrolyte inside the battery, more free electrolyte remaining in the upper and lower parts of the shell will be sucked in due to the siphon phenomenon of the diaphragm, which will cause the polymer layer of the diaphragm that has been polymerized and adhered to the positive electrode to be bubbled, and the battery cell will be damaged during the cycle. The phenomenon of bulging and deformation at the upper and bottom positions will lead to lithium precipitation at the deformation position, accompanied by a sharp decrease in the battery cycle capacity retention rate

[0003] Most of the existing mobile phones use non-removable built-in batteries. Once the battery is partially deformed, it will be light on the top of the screen, resulting in white spots in certain positions when touching the screen. In severe cases, lithium will be deposited due to the deformation. The probability of battery fire and explosion increases during use, and such accidents have been reported frequently in recent years

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