Negative plate with sandwich structure and lithium ion battery comprising negative plate

Abstract

The invention provides a negative plate with a sandwich structure and a lithium ion battery comprising the negative plate. When a conventional lithium ion battery is subjected to a needling test, an internal short circuit occurs, a large amount of heat is generated in a short time due to relatively large current density of the internal short circuit, thermal shrinkage of a diaphragm is caused, andfinally thermal runaway of the battery is caused. A lithium titanate layer is contained in the negative plate, lithium can be rapidly removed at the moment of internal short circuit to form an air-state insulator, the resistance of the negative plate is sharply increased in the process, the short-circuit current can be reduced, and then the needling safety of the lithium ion battery can be improved. A silicon material layer is contained in the negative plate, lithium dendrites can be consumed through reaction when the silicon material layer makes contact with the lithium dendrites, the situation that the negative plate seriously separates out lithium to form a large number of lithium dendrites in the overcharge process of the battery cell is avoided, and internal short circuit caused by the fact that the lithium dendrites pierce a diaphragm is further avoided.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a negative electrode sheet with a sandwich structure and a lithium ion battery including the negative electrode sheet. Background technique [0002] In recent years, with the intensification of the energy crisis and the deterioration of the natural environment, the application of lithium-ion batteries in the fields of electric vehicles and energy storage equipment has gradually attracted attention. However, due to the safety problems of lithium-ion power batteries, many electric vehicle And spontaneous combustion and explosion accidents of hybrid electric vehicles, which seriously restrict the promotion speed of lithium-ion batteries in the field of new energy. [0003] The safety performance of batteries is usually verified by overcharging, furnace temperature and acupuncture tests. In order to improve the safety of the battery cell during the overchar...

AI Technical Summary

Problems solved by technology

In order to improve the safety of the battery cell during the overcharge test, it is common practice in this field to add an overcharge additive to the electrolyte of the lithium-ion battery. Although this operation can solve the problem of overcharge, the acupuncture and furnace temperature Security is still poor

The usual way to improve the safety of furnace temperature testing is to use high-temperature-resistant diaphragms (such as polyimide diaphragms, polyphenylene sulfide diaphragms, aramid resin diaphragms, polyaramid diaphragms, etc.), but such diaphragms are expensive and expensive. The safety of overcharging is not good, and it may also affect the cycle life of the battery

Positive electrode primer method is the usual method to improve the safety of battery acupuncture, but it cannot take into account the safety of overcharging and furnace temperature

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