Lithium ion secondary battery cathode, preparation method thereof and lithium ion secondary battery

Abstract

The invention belongs to the field of lithium ion secondary batteries and provides a lithium ion secondary battery cathode which comprises cathode current collectors and silicon films deposited on the surface of the cathode current collectors, wherein the amount of the current collectors is two, each current collector is provided with a via hole, and the silicon films are deposited on the two surfaces of each current collector, at least one layer of the silicon film is provided with the via hole, and the average pore size of the via hole on the silicon film is 0.2-0.6mm; and the cathode current collectors are mutually overlaid, and at least one layer of silicon film is deposited on the adjacent surfaces of every two overlaying cathode current collectors. The lithium ion secondary battery cathode is adopted to overcome the defect of poor circulation performance of a battery when the silicon films are used as cathode active substances to greatly enhance the circulation performance of the battery under the room temperature: under the room temperature, the capacity retention can reach 100 percent after 200 charging and discharging circulations, and the capacity of the battery is increased less than the initial discharging capacity after 200-500 circulations.

Description

technical field [0001] The invention relates to a lithium ion secondary battery negative pole, a preparation method thereof and a lithium ion secondary battery containing the negative pole. Background technique [0002] Silicon materials have become one of the research hotspots of high-capacity lithium-ion secondary battery anode materials because their lithium storage capacity (theoretical capacity 4200mAh / g) is much larger than graphite-based carbon materials (theoretical specific capacity 372mAh / g). However, during the charge-discharge cycle, the reversible formation and decomposition of the Li-Si alloy is accompanied by a huge volume change, which will cause the mechanical splitting of the alloy (creating cracks and pulverization), resulting in the collapse of the material structure and the peeling off of the electrode material. The electrode material loses electrical contact, causing the cycle performance of the electrode to drop sharply, and finally leads to the failur...

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Problems solved by technology

[0003] In order to solve the technical problem of poor battery cycle performance when silicon materials are used in the negative electrode of lithium-ion secondary batteries, the present invention firstly provides a negative electrode of lithium-ion secondary batteries, including a negative electrode current collector and silicon deposited on the surface of the negative electrode current collector. Thin film, the number of negative electrode current collectors is at least 2, each negative electrode current collector has a through hole, and silicon films are deposited on the two surfaces of each negative electrode current collector; the negative electrode current collectors are stacked on each other, and every 2 At least one layer of silicon film is deposited on the adjacent surfaces of the stacked negative electrode current collectors

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