Non-aqueous electrolyte and secondary battery thereof

Abstract

The invention provides a non-aqueous electrolyte and a secondary battery thereof, the non-aqueous electrolyte comprises a lithium salt, a non-aqueous organic solvent and an additive, the additive comprises a cyclic amide compound represented by a structural formula I, a structural formula II or a structural formula III, r1 to R8 are respectively and independently selected from hydrogen, halogen, substituted or unsubstituted methyl and substituted or unsubstituted C2-C9 alkyl. The cyclic amide compound provided by the invention can be reduced to form a silicon-containing amide compound, and the compound has good thermal stability and can isolate direct contact between an electrolyte and a positive electrode material at a high temperature, so that decomposition of the electrolyte is inhibited. In addition, by introducing a-Si-N-CO-structure, the toughness of chemical bonds can be increased, so that gas production caused by instability of aminoacyl groups under high voltage and high voltage is avoided. Meanwhile, the cyclic amide compound contains a Si-N bond structure, so that free water and HF in a battery system can be removed, and the performance of the positive electrode material is improved.

Description

technical field [0001] The invention relates to the field of energy storage devices, in particular to a non-aqueous electrolyte and a secondary battery thereof. Background technique [0002] With the continuous increase in the capacity requirements of secondary batteries for pure electric vehicles, hybrid electric vehicles and portable energy storage devices, people expect to develop secondary batteries with higher energy density and power density to achieve energy storage and long-term battery life. [0003] In addition to the improvement of existing materials and battery manufacturing process, high-voltage (4.35-5V) cathode materials are one of the more popular research directions, which can achieve high energy density of batteries by increasing the charging depth of cathode active materials. Among them, high-nickel cathode materials (nickel content higher than 0.6) are more commonly used cathode materials due to their higher capacity. Under the high voltage system, the c...

AI Technical Summary

Problems solved by technology

Under the high voltage system, the conventional electrolyte is prone to side reactions, which will deteriorate the performance of the positive electrode material and affect the electrochemical performance of the secondary battery.

At the same time, the secondary battery under the high voltage system also has strict water control. Under the high voltage, the excess water is easy to react with the lithium salt to form HF, thereby destroying the formation of the interfacial film and deteriorating the battery performance.

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