Additive for lithium ion battery electrolyte, electrolyte and lithium ion battery

Abstract

The invention provides an additive for a lithium ion battery electrolyte, the electrolyte and a lithium ion battery, the additive comprises a first additive and a second additive, the first additive is a compound with a structural formula as shown in a formula I, and the second additive is an unsaturated alkane compound comprising at least two silicon-oxygen structures. Compared with the existing electrolyte additive, the additive provided by the invention can generate a stable and low-impedance interfacial film through the combined action of the first additive and the second additive on the surfaces of the positive electrode and the negative electrode respectively, can improve the hot box performance and the low-temperature performance of the lithium ion battery, and simultaneously considers the cycle performance and the storage performance.

Description

technical field [0001] The invention relates to the field of lithium batteries, in particular to an additive for an electrolyte of a lithium ion battery, an electrolyte and a lithium ion battery. Background technique [0002] Lithium-ion batteries are widely used in electronic digital, electric vehicles, energy storage applications and aerospace fields due to their high operating voltage, long cycle life, high energy density, and environmental friendliness. As the "blood vein" of lithium-ion batteries, electrolyte is one of the important raw materials for lithium-ion batteries. It is responsible for the transmission capacity between the positive and negative electrodes and plays a crucial role in the performance of lithium-ion batteries. Salts and additives play an important role in low temperature, cycle, storage and safety performance of lithium-ion batteries. [0003] Under low temperature conditions, linear carbonates and carboxylates tend to have low dielectric constan...

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Problems solved by technology

[0003] Under low temperature conditions, due to the characteristics of their own structures, linear carbonates and carboxylates often have low dielectric constants, and the solubility of lithium salts is low at low temperatures, resulting in a decrease in the migration rate of lithium ions, resulting in poor low temperature performance.

In addition, the hot box test is one of the important test items for lithium-ion batteries at present. At the limit temperature (≥130°C), due to the continuous intensification of the internal chemical reaction of the battery, the heat cannot be released, causing the lithium-ion battery to catch fire or even explode, bringing serious safety hazards , the current solution is mainly to add stable film-forming additives to improve the stability of positive electrode materials and reduce side reactions. However, stable film-forming additives will increase the impedance of the battery system and affect the kinetic performance

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