Method for prolonging cycle life of lithium ion battery

Abstract

The invention relates to a method for prolonging the cycle life of a lithium ion battery, and a formation method mainly comprises two steps: 1, after liquid injection of the lithium battery is completed, standing is performed, then pressure is applied to the lithium battery, stepped charging is performed under the conditions of different formation temperatures and formation charging currents, and after charging is completed, exhausting, vacuumizing and sealing are performed; 2, pressure is applied to the lithium battery, and then charging and discharging are performed for 1-3 cycles under the conditions of certain formation temperature, formation charging and discharging current and formation voltage range; and the low-impedance SEI film is prepared by regulating and controlling the growth mode of the SEI film, so that the formation method for prolonging the cycle life of the aluminum-plastic shell soft package lithium ion battery is realized. The method has the beneficial effects that the method is applied to MCM and NCA soft package battery systems; and by regulating and controlling the growth of the SEI film in the formation process, the SEI film which is moderate in thickness, uniform, compact and low in impedance is obtained, and the cycle life of the battery is remarkably prolonged.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a method for improving the cycle life of lithium-ion batteries. Background technique [0002] At present, energy storage devices have developed from primary batteries to secondary batteries, and among the secondary batteries, lithium-ion batteries are the mainstream. Due to the advantages of high capacity, high specific energy, high power density, portability, and easy manufacturing, lithium-ion batteries have deeply penetrated into 3C electronic products, power battery products, energy storage products and other fields. The positive electrode materials in lithium-ion batteries account for a large proportion. At present, the positive electrode materials of lithium-ion batteries mainly include lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, nickel-cobalt-manganese ternary material (NCM), nickel-cobalt-aluminum ternary material (NCA)...

AI Technical Summary

Problems solved by technology

For example, the research group of Professor Won II Park of Hanyang University in South Korea formed a stable SEI film by controlling the potential gradient on the electrochemical interface (Chang W J, Kim S H, Hwang J, et al. Controlling electric potential to inhibit solid-electrolyte interphase formation on nanowire anodes for ultrafast lithium-ion batteries[J].Nature communications,2018,9(1):3461.), but the method is complicated to operate and the cost is difficult to control; RODRIGUES et al found that using ionic liquid electrolyte and raising the formation temperature to 90°C , it will make the SEI film formed on the graphite surface thicker and have better thermal stability, but the impedance will increase, the rate performance will decrease, and the cost will also increase (Rodrigues M T F, Sayed F N, Gullapalli H, et al. High-temperature solid electrolyte interphases(SEI)in graphite electrodes[J].Journal of Power Sources,2018,381:107-115.)

Images