Safety layer and lithium secondary battery

Abstract

The invention provides a safety layer and a lithium secondary battery. The safety layer is used to separate the positive electrode sheet and the negative electrode sheet. The safety layer includes at least two electronically insulating ion-conducting layers and at least one absorbing layer. The absorbing layer is located between every two adjacent layers of electron-insulating ion-conducting layers. In the safety layer, the side close to the positive electrode sheet and the negative electrode sheet respectively is an electronic insulating ion conduction layer. The absorbing layer includes substances capable of reversibly deintercalating lithium, and the conductivity of the absorbing layer is not less than 10 ‑1 S / m. After the safety layer is applied to lithium secondary batteries, it can effectively alleviate the growth of lithium dendrites, reduce the risk of short circuits in lithium secondary batteries in various extreme and complex environments, prolong the cycle life of lithium secondary batteries, and improve Safety performance of lithium secondary batteries. At the same time, the safety layer of the present invention will not 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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