Positive pole piece and electrochemical device

Abstract

The invention relates to a positive pole piece and an electrochemical device. The positive pole piece comprises a metal current collector, a positive active material layer and a safety coating arranged between the metal current collector and the positive active material layer, wherein the safety coating comprises a polymer matrix, a conductive material and an inorganic filler, the positive activematerial layer contains Li<1+x>NiaCobMe<1-a-b>O2, x is greater than or equal to -0.1 and less than or equal to 0.2, a is greater than or equal to 0.6 and less than 1, b is greater than 0 and less than1, (1-a-b) is greater than 0 and less than 1, and Me is selected from at least one of Mn, Al, Mg, Zn, Ga, Ba, Fe, Cr, Sn, V, Sc, Ti and Zr; and the metal current collector is an aluminum-containing porous current collector. The positive pole piece can improve the electrical performance and safety performance of an electrochemical device (such as a capacitor, a primary battery or a secondary battery).

Description

technical field [0001] The invention belongs to the technical field of electrochemistry, and more specifically, the invention relates to a positive pole piece and an electrochemical device comprising the positive pole piece. Background technique [0002] Lithium-ion batteries are widely used in electric vehicles and consumer electronics due to their advantages such as high energy density, high output power, long cycle life and low environmental pollution. [0003] At present, ternary materials have become one of the main positive electrode materials used in commercial lithium-ion batteries, especially in the field of lithium-ion batteries for electric vehicles. High-nickel ternary materials (such as NCM622 and NCM811) are expected to become the main cathode materials for a new generation of lithium-ion batteries for electric vehicles due to their high energy density. However, the thermal stability of high-nickel ternary materials is poor, and strong oxidizing substances wil...

AI Technical Summary

Problems solved by technology

Yet in this improved mode, when coating active material slurry on the surface of PTC material layer, the solvent (such as NMP etc.) in the slurry will make the PTC material (usually polyethylene, polypropylene or ethylene propylene) in the PTC layer Copolymers and other materials) dissolve and enter the upper active material layer, which not only makes the PTC layer lose the PTC effect, but also deteriorates the electrical properties

In addition, during the compaction step in the pole piece manufacturing process, the PTC material layer is easily squeezed to the edge, resulting in direct contact between the electrode active material layer and the metal current collector, thereby losing the effect of improving safety performance.

This traditional PTC material layer has been proven not suitable for high nickel ternary materials

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