Lithium-ion secondary battery

Abstract

The invention discloses a lithium ion secondary battery. The lithium ion secondary battery includes a positive pole piece, a negative pole piece, a separator and an electrolyte solution, the positive pole piece includes a positive active material layer, and the negative pole piece includes a negative active material layer. Wherein, the positive electrode active material of the positive electrode active material layer includes a lithium manganese-based positive electrode active material; the negative electrode active material layer and / or the electrolyte include a sulfur-containing compound, so that the sulfur-containing compound is in the negative electrode The active material layer forms a solid electrolyte interface film containing sulfur elements, and the mass percentage v of the sulfur element in the negative electrode active material layer containing the interface film is equal to the mass percentage u of the manganese element in the positive electrode active material. Satisfy: v=0.018u+ω, wherein, the units of u and v are both wt%, and ω is 0.01-2. The lithium ion secondary battery of the present invention can take into account high safety performance, cycle performance and storage performance at the same time.

Description

technical field [0001] The invention belongs to the technical field of batteries, in particular to a lithium ion secondary battery. Background technique [0002] Lithium-ion secondary batteries can provide stable voltage and current, have a high voltage platform, high energy density and wide temperature range, no memory effect, and are environmentally friendly and easy to carry, and are widely used in various consumer electronics products, Electric vehicles and mechanical equipment. [0003] The safety performance of the lithium-ion secondary battery can be improved by using a positive electrode active material containing manganese. However, since the manganese in the positive electrode is prone to disproportionation reaction, the generated manganese ions dissolve in the electrolyte and migrate to the negative electrode. Lithium ion exchange occurs, occupying the lithium intercalation position of the negative electrode, and is not easy to come out, resulting in a decrease i...

AI Technical Summary

Problems solved by technology

[0003] The safety performance of lithium-ion secondary batteries can be improved by using a positive electrode active material containing manganese. However, since the manganese in the positive electrode is prone to disproportionation reaction, the generated manganese ions dissolve in the electrolyte and migrate to the negative electrode. The lithium ion exchange occurs, occupies the position of lithium intercalation in the negative electrode, and is not easy to come out, resulting in a decrease in the lithium storage capacity of the negative electrode, and the lithium ions released by ion exchange will no longer be able to participate in the deintercalation between the positive and negative electrodes, resulting in capacity loss and deterioration of lithium. The cycle performance and storage performance of ion secondary batteries are more seriously affected at high temperatures (above 40°C)

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