secondary battery

Abstract

The invention provides a secondary battery, and the secondary battery comprises a positive electrode piece, a negative electrode piece, an isolating membrane and an electrolyte; the positive electrodepiece comprises a positive current collector and a positive diaphragm which is arranged on the surface of the positive current collector and contains a positive active material. The electrolyte comprises an additive A and an additive B, wherein the additive A is selected from one or more of cyclic sultone compounds shown in a formula 1 and a formula 2, and the additive B is selected from one or two of lithium difluoro bis (oxalato) phosphate and lithium tetrafluoro (oxalato) phosphate. An inorganic dielectric layer is arranged on the surface, far away from the positive electrode current collector, of the positive electrode diaphragm, wherein the inorganic dielectric layer is made of an inorganic dielectric material, and the thickness T1 of the inorganic dielectric layer ranges from 0.05 micrometer to 1 micrometer. According to the invention, the gas production rate of the battery can be reduced, the increase of direct-current internal resistance in battery circulation and storage processes is significantly inhibited, and the battery is ensured to have good power performance and service life.

Description

technical field [0001] The invention relates to the field of batteries, in particular to a secondary battery. Background technique [0002] Due to the characteristics of high energy density, long cycle life, and no pollution, lithium-ion batteries have broad application prospects in consumer electronics, power vehicle batteries, and energy storage power supplies. [0003] During the use of lithium-ion batteries, positive active materials with strong oxidation activity can easily oxidize the electrolyte, causing the electrolyte to decompose and generate gas. In the prior art, 1,3-propane sultone (PS) is usually added to the electrolyte, which can form a passivation film on the surface of the positive electrode and reduce the oxidation activity of the positive electrode active material, thereby reducing the gas production of the battery. However, the passivation film formed by 1,3-propane sultone on the surface of the positive electrode is not durable enough, resulting in con...

AI Technical Summary

Problems solved by technology

However, the passivation film formed by 1,3-propane sultone on the surface of the positive electrode is not durable enough, resulting in continuous oxidation and decomposition during the cycle and storage of lithium-ion batteries As the resistance continues to increase, the acceleration performance and power performance of lithium-ion batteries become worse, which seriously affects the use of lithium-ion batteries.

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