Method for improving formation interface of lithium ion battery

Abstract

The invention provides a method for improving a formation interface of a lithium ion battery, applied to the technical field of lithium ion. The method comprises the following process steps: performing primary liquid injection after a battery cell of the lithium ion battery is subjected to vacuum baking, and vacuumizing in the primary liquid injection process; standing before formation and high temperature after primary liquid injection; after standing before high temperature is finished, carrying out primary clamp formation; standing for a period of time, and carrying out secondary clamp formation, wherein the clamp forces of the two times of clamp formation are the same but the charging currents are different; after secondary clamp formation is finished, carrying out post-forming high-temperature standing to form a high-quality SEI film in order to improve the formation interface of the lithium ion battery. The method is simple in step, the quality of the formation interface is improved, and finally, the negative phenomena such as brown spots and lithium precipitation do not appear on the anode plate of the battery any more; and the electrochemical performance of the battery is improved, the cycle life of the battery is correspondingly prolonged, and the cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of lithium ions, and more specifically relates to a method for improving the formation interface of a lithium ion battery. Background technique [0002] The battery cell of lithium-ion battery is a secondary battery cell that can be repeatedly charged and discharged. It is composed of cathode and anode plates, separator, electrolyte, mechanical parts and other main components. In the production process of liquid lithium-ion batteries, formation is one of the most important processes. During the formation process, the lithium-ion battery will be charged and discharged for the first time to activate the battery cell. At this time, the electrode material will be in solid-liquid with the electrolyte. The phase interface reacts to form a passivation layer covering the electrode surface; this passivation film has the characteristics of a solid electrolyte and is an electronic insulator, but it is an excellent cond...

AI Technical Summary

Problems solved by technology

In the production process of liquid lithium-ion batteries, formation is one of the most important processes. During the formation process, the lithium-ion battery will be charged and discharged for the first time to activate the battery cell. At this time, the electrode material will be in solid-liquid with the electrolyte. The phase interface reacts to form a passivation layer covering the electrode surface; this passivation film has the characteristics of a solid electrolyte and is an electronic insulator, but it is an excellent conductor of Li+, and Li+ can pass through the passivation layer freely. Intercalation and extraction, so it is also called solid electrolyte phase interface film, referred to as SEI film; and in actual formation, LFP (English: LithiumIron Phosphate, LiFePO4, Chinese: lithium iron phosphate) lithium-ion batteries often have bad interfaces. That is, "brown spots" appear on the anode sheet, seriously affecting battery capacity, cycle life and other performance

Images