Non-aqueous electrolyte and lithium secondary battery using the same

Abstract

The invention discloses a non-aqueous electrolyte and a lithium secondary battery using the same. The non-aqueous electrolyte contains lithium electrolyte salt, a non-aqueous organic solvent, a cesium salt compound additive and a film forming additive; the cesium salt compound additive accounts for, by weight, 0.01%-20% of the total amount of the non-aqueous organic solvent. In the non-aqueous electrolyte, the cesium salt compound additive can increase ionic conductivity of the electrode surface during charging and discharging, impedance formed on the electrode surface to an SEI film by a conventional film-forming additive is lowered, cyclic stability of the lithium secondary battery is well maintained, and low-temperature property and rate performance are obviously improved.

Description

technical field [0001] The invention belongs to the field of lithium secondary batteries, and relates to a nonaqueous electrolytic solution and a lithium secondary battery using the nonaqueous electrolytic solution. The non-aqueous electrolytic solution involved in the invention can significantly improve the low-temperature performance and rate performance while improving the long-term cycle performance of the lithium secondary battery. Background technique [0002] Lithium secondary batteries have the advantages of high specific energy, high specific power and long cycle life, and have been widely used in portable electronic devices. With the increasingly prominent energy and environmental issues, the application of lithium secondary batteries in the field of electric vehicles and energy storage has developed rapidly. Lithium secondary batteries for electric vehicles require a long cycle life. In lithium battery electrolytes, adding film-forming additives can inhibit elect...

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Problems solved by technology

Lithium secondary batteries for electric vehicles require a long cycle life. In lithium battery electrolytes, adding film-forming additives can inhibit electrolyte decomposition and improve cycle life, but at the same time it will also increase the impedance of the electrode surface; especially in low temperature conditions However, due to the significant increase in interface impedance, the charge and discharge capacity and rate performance of the battery will be greatly reduced. At the same time, it may cause a large amount of heat generation in the battery, which will bring safety hazards and limit the application of lithium secondary batteries in the field of electric vehicles.

[0003] In the field of lithium secondary battery electrolyte, researchers often add film-forming additives with low interface impedance to reduce the increase in SEI film impedance. However, for stable SEI films, the interface impedance is often high, so looking for an improvement Electrolyte additives for interfacial impedance of SEI films are necessary

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