Negative electrode sheet, its preparation method and electrochemical device

Abstract

The invention discloses a negative electrode sheet, a preparation method thereof and an electrochemical device. The negative electrode sheet includes a negative electrode current collector, a negative electrode active material layer and an inorganic dielectric layer which are laminated; the negative electrode active material layer includes an opposite first surface and The second surface, wherein the first surface is arranged away from the negative electrode current collector; the inorganic dielectric layer is arranged on the first surface of the negative electrode active material layer, and the first dielectric layer in the inorganic dielectric layer is located on the outer surface of the negative electrode active material layer and The thickness is 30nm≤T 1 ≤1000nm, the second dielectric layer is located on the inner wall of at least a part of the pores inside the negative electrode active material layer and the thickness is 0nm<T 2 ≤500nm, the second dielectric layer extends from the first surface to the second surface and the extension depth H is the same as the thickness T of the first dielectric layer 1 Meet: 0.5≤H / T 1 ≤5. The negative pole piece provided by the invention is used in an electrochemical device, which can make the electrochemical device take into account both excellent safety performance and cycle performance.

Description

technical field [0001] The invention belongs to the technical field of energy storage devices, and in particular relates to a negative pole piece, a preparation method thereof and an electrochemical device. Background technique [0002] Electrochemical devices can convert chemical energy into electrical energy, have stable voltage and current, reliable performance, simple structure, and easy to carry. They have become the main power source of various consumer electronics and electric products, and are widely used in people's production and every aspect of life. In recent years, the market has put forward higher and higher requirements for the cycle performance and safety performance of electrochemical devices. [0003] However, during the circulation process of the existing electrochemical devices, there are many side reactions between the interface between the electrolyte and the negative electrode, which causes the electrolyte to decompose and produce gas, which deteriora...

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Problems solved by technology

[0003] However, during the circulation process of the existing electrochemical devices, there are many side reactions between the interface between the electrolyte and the negative electrode, which causes the electrolyte to decompose and produce gas, which deteriorates the safety performance of the electrochemical device. At the same time, the electrolyte cations on the negative electrode are continuously consumed. The irreversible capacity of the device continues to increase, resulting in a rapid decline in its cycle life

Moreover, due to the poor transport performance of electrolyte cations at the negative electrode, it will also lead to the formation of metal dendrites at the negative electrode interface, which is prone to short circuits in the electrochemical device and further deteriorates the safety performance of the electrochemical device.

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