Negative pole piece, preparation method thereof and electrochemical device

Abstract

The invention discloses a negative pole piece, a preparation method thereof and an electrochemical device. The negative pole piece comprises a negative pole current collector, a negative pole active material layer and an inorganic dielectric layer which are stacked; the negative pole active material layer comprises a first surface and a second surface which are opposite to each other, wherein thefirst surface is far away from the negative pole current collector; the inorganic dielectric layer is arranged on the first surface of the negative pole active material layer; the inorganic dielectriclayer is composed of an inorganic dielectric material; the inorganic dielectric layer comprises a first dielectric layer located on the outer surface of the negative pole active material layer; the thickness of the first dielectric layer is 30-1000 nm; the compaction density of the negative pole piece is 1.2 g/cm <3>-2.0 g/cm<3>; the porosity of the negative pole piece is 25%-45%; and the electrolyte infiltration rate of every 10cm*10cm area of the negative pole piece is greater than or equal to 2 microgram/s. The negative pole piece provided by the invention is used for an electrochemical device, so that the electrochemical device has excellent safety performance and high cycle performance at the same time.

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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