Safety layer and lithium secondary battery

Abstract

The invention provides a safety layer and a lithium secondary battery. The safety layer is used for separating a positive electrode sheet and a negative electrode sheet, and comprises at least two layers of electrically insulating ion conducting layers and at least an absorption layer, wherein the absorption layer is positioned between each two adjacent two electrically insulating ion conducting layers, one sides respectively close to the positive electrode sheet and the negative electrode sheet are the electrically insulating ion conducting layers in the safety layer, the absorption layer comprises a substance capable of reversibly deintercalating lithium, and the conductivity of the absorption layer is not less than 10<-1> S/m. According to the present invention, after the safety layer is applied in the lithium secondary battery, the growth of the dendritic lithium can be effectively alleviated, the risk of the short circuit of the lithium secondary battery in various extreme and complicated environments is reduced, the cycle life of the lithium secondary battery is prolonged, and the safety performance of the lithium secondary battery is increased; and the safety layer cannot reduce the energy density of the lithium secondary battery.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to a safety layer and a lithium secondary battery. Background technique [0002] At present, the application range of lithium secondary batteries is becoming wider and wider, and the conditions and environments of use are becoming more and more complex. For example, it needs to meet high-rate charge and discharge or have a long cycle life or meet the use in low-temperature environments, so one-time use is not appropriate. Or misoperation leads to an increasing risk of lithium deposition at the negative electrode of the lithium secondary battery, and during the cycle of the lithium secondary battery, due to the influence of its own polarization, the risk of lithium deposition at the negative electrode in the middle and late stages of the cycle increases significantly, resulting in lithium secondary battery The risk of internal short circuit of the battery is significantly increased...

AI Technical Summary

Problems solved by technology

[0003] In actual use, although coating the oxide ceramic layer on the conventional polyolefin separator can reduce the risk of lithium precipitation in the initial cycle of lithium secondary batteries to a certain extent, as the cycle progresses, the precipitated lithium will continue to accumulate on the negative electrode. Therefore, it still cannot fundamentally solve the problem; especially in the later stage of the cycle, when encountering complex conditions of use, such as charging when the temperature is low (such as winter), the growth rate of lithium dendrites is very fast, and the safety risk will be greater

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