Lithium ion battery electrolyte and lithium ion battery

Abstract

The invention relates to a lithium ion battery electrolyte and a lithium ion battery, and belongs to the technical field of lithium ion batteries. The lithium ion battery electrode comprises an organic solvent, an electrolyte lithium salt, a low-impedance additive and a functional additive, wherein the low-impedance additive comprises lithium difluorophosphate and lithium difluoro bis(oxalato) phosphate, the functional additive is an arbitrary one or a combination of tris(trimethylsilyl) borate and tris(trimethylsilyl) phosphate, and the functional additive accounts for 0.1-4% of the total mass of the lithium ion battery electrolyte. The lithium ion battery electrolyte can participate in negative electrode film formation, the interface impedance of the electrolyte is reduced, and the low-temperature performance of the electrolyte is improved; and a flexible and high-temperature stable electrode interface film also can be formed on a surface of a high-capacity silicon carbon composite negative electrode material, the breakage of an SEI film caused by silicon expansion during the circulation process is timely repaired, and the cycle property of the silicon carbon negative electrode lithium ion battery is improved.

Description

technical field [0001] The invention relates to a lithium ion battery electrolyte and a lithium ion battery, belonging to the technical field of lithium ion batteries. Background technique [0002] Since the commercialization of lithium-ion batteries in the 1990s, they have received extensive attention due to their superior performance in all aspects. However, with the gradual development of electric vehicles, people have put forward higher requirements for the energy density of lithium-ion batteries. [0003] The current commercial lithium-ion battery anode material uses graphite anode material, which has a low charge-discharge specific capacity and a theoretical capacity of 372mAh / g, which cannot meet the current demand for high-energy-density chemical power sources for electric vehicles. Due to its high theoretical specific capacity (4200mAh / g), low delithiation potential (<0.5V), and abundant content, silicon-based materials have become one of the most ideal candidat...

AI Technical Summary

Problems solved by technology

The electrolyte solution takes into account the high temperature performance and low temperature performance of the battery by adding the synergistic effect between the gas expansion inhibitor and the low impedance additive, but the low temperature performance of the electrolyte described in the above technology is only the cycle performance at 5°C, and silicon Content ≤ 8%, unable to meet the needs of batteries for high energy density and wider test temperature range, so there is an urgent need to develop silicon-based negative electrodes with higher silicon content and better performance at low temperatures below 0°C without deteriorating high-temperature performance Electrolyte

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