PC (Propylene Carbonate)-based high-voltage electrolyte and lithium ion battery

Abstract

The invention provides PC (Propylene Carbonate)-based high-voltage electrolyte. The PC-based high-voltage electrolyte comprises a non-aqueous solvent, and a lithium salt and an additive which are dissolved into the non-aqueous solvent; the non-aqueous solvent comprises propylene carbonate (PC) and linear carboxylate; the mass percent content of the propylene carbonate (PC) in the electrolyte is 15%-50%; the additive comprises fluoroethylene carbonate, ethylene sulfate and a dinitrile compound. A solvent system and the additive are optimally combined and used to generate a cooperative effect and are used for a lithium ion battery, so that good cycle life, low-temperature discharging properties and high-temperature storage properties of the battery can still be kept under high voltage.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery preparation, in particular to a PC-based high-voltage electrolyte and a lithium-ion battery. Background technique [0002] Lithium-ion battery is the most competitive battery of the new generation, known as "green energy", and is the preferred technology to solve contemporary environmental pollution and energy problems. In recent years, lithium-ion batteries have achieved great success in the field of high-energy batteries, but consumers still expect batteries with higher comprehensive performance, which depends on the research and development of new electrode materials and electrolyte systems. [0003] At present, electronic digital products such as smartphones and tablet computers have higher and higher energy density requirements for batteries, making it difficult for commercial lithium-ion batteries to meet the requirements. The energy density of the battery can be improved by: se...

AI Technical Summary

Problems solved by technology

Among them, HF will corrode the positive electrode, resulting in the dissolution of metal ions, thereby destroying the structure of the positive electrode material, resulting in capacity loss; Dissolved into the electrolyte, thereby destroying the structure of the positive electrode material, resulting in capacity loss

At the same time, the metal ions dissolved into the electrolyte can easily pass through the SEI to the negative electrode to obtain electrons and be reduced to simple metals, thereby destroying the structure of the SEI, resulting in a continuous increase in the negative electrode impedance, increased battery self-discharge, and increased irreversible capacity. deterioration

[0005] U.S. Patent No. 5,471,862 replaces the ethers in the electrolyte with chain carboxylate to form an electrolyte containing a mixed solvent of chain carboxylate, cyclic carbonate and chain carbonate, avoiding side reactions between ethers and the negative electrode , significantly improved the low-temperature cycle performance and high-temperature storage performance of lithium-ion batteries, but carboxylate solvents will have unavoidable side reactions with the negative electrode

[0006] U.S. Patent US 2008 / 0311481Al (Samsung SDI Co., Ltd) discloses an ether / aryl compound containing two nitrile groups, which improves the inflation of the battery under high voltage and high temperature conditions and improves high temperature storage performance, but its low temperature performance remains to be seen. Improve

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