Ethylene sulfate additive contained high-voltage functional electrolyte and preparation method and application therefor

Abstract

The invention discloses an ethylene sulfate additive contained high-voltage functional electrolyte and a preparation method and an application therefor, and belongs to the field of the lithium ion battery. The electrolyte is obtained by adding a functional additive to a common electrolyte; the common electrolyte is formed by a cyclic carbonate solvent, a linear carbonate solvent and a conductive lithium salt; and the functional additive adopts ethylene sulfate. According to the functional electrolyte, the ethylene sulfate additive is taken as the high-voltage film-forming additive for the lithium ion electrolyte; the additive is relatively high in reduction potential, so that a compact and stable SEI film layer can be formed on the surface of a negative electrode in the first charge-discharge process; therefore, the negative electrode surface film is optimized, the resistance between the negative electrode and the electrolyte is lowered, and the surface activity of the electrode is restrained, so that the further contact between the electrolyte and the electrode active material is restrained consequently, and the oxidization and decomposition of the electrolyte main body solvent on the electrode surface is lowered; and the cycling performance of the electrolyte additive contained lithium ion battery under 3-4.45V can be improved.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and in particular relates to a high-voltage functional electrolytic solution containing vinyl sulfate additive, a preparation method and application thereof. Background technique [0002] Lithium-ion batteries have the advantages of high energy density, high operating voltage and long cycle life. At present, the positive electrode materials of commercial lithium-ion batteries include lithium manganese oxide, lithium cobalt oxide, lithium iron phosphate, and ternary materials. The charging cut-off voltage generally does not exceed 4.2V. With the advancement of technology and the continuous development of the market, It is increasingly important and urgent to increase the energy density of lithium batteries. In addition to the improvement of existing materials and battery production processes, high-voltage (>4.5V) cathode materials are one of the more popular research directions, mainly to ...

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Problems solved by technology

[0004] However, while increasing the voltage of the positive electrode material, the electrical performance of the battery charge-discharge cycle is declining. On the one hand, the reason is that the structure of the lithium cobalt oxide material is not stable enough under high voltage conditions, and on the other hand, the transition metal cobalt ions will be released from the battery. The positive electrode dissolves through the separator and deposits and reduces on the negative electrode, destroying the interface film on the surface of the negative electrode, thereby destroying the graphite negative electrode particles

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