Lithium supplementing layer and negative pole piece thereof and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries. The invention especially relates to a a lithium supplementing layer and a negative pole piece thereof and the lithium ion battery. The lithium supplementing layer is formed by sequentially connecting a transition layer, an oxide layer and a surface layer; the surface layer comprises a proper amount of organic materials and filling materials; the winding temperature of the negative pole piece can be reduced, the oxide layer substance in the lithium supplementing layer is used for providing an additional lithium source, the lithium source can be continuously supplemented in the circulation process after liquid injection, the activity of the lithium layer is improved, meanwhile, a filling substance contained in the surfacelayer can effectively play a role in restraining expansion of an active substance, and the cycle performance of the battery is improved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and more specifically relates to a negative electrode lithium replenishment layer, a negative electrode sheet thereof, and a lithium ion battery. Background technique [0002] Lithium-ion batteries are widely used in the field of portable power sources due to their high energy density and long cycle life. However, with the development of large-scale mobile power applications such as electric vehicles and drones, the development of lithium-ion batteries with higher energy density is a major issue that needs to be solved urgently. [0003] During the first charging process of the battery, the solid electrolyte layer (SEI) formed on the surface of the negative electrode will consume a large amount of lithium source and convert lithium into inactive lithium-containing compounds such as lithium carbonate, lithium fluoride and alkyllithium, resulting in The loss of recyclable lithium red...

AI Technical Summary

Problems solved by technology

At present, the way of lithium supplementation is to thin the lithium foil on the surface of the pole piece by rolling, but this process will cause two problems: 1. After the lithium layer is rolled, it will adhere to the surface of the pole piece (negative electrode / positive electrode). The side reactants of the sheet active material have an exothermic reaction with oxygen in the air, which leads to an increase in the temperature of the electrode sheet during the electrode manufacturing process, resulting in a production safety risk; 2. The electrode sheet made of new active material materials such as silicon-based / tin-based , due to the expansion of the silicon base itself during cycling, the SEI film is unstable, resulting in poor cycle performance

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