High voltage electrolyte containing benzonitrile additive and preparation method of high voltage electrolyte

Abstract

The invention discloses high voltage electrolyte containing a benzonitrile additive, and a preparation method of the high voltage electrolyte. The high voltage electrolyte is prepared from the following raw materials in parts by mass: 1 part of cyclic carbonate, 1 part of linear carbonate diethyl carbonate, 1 part of ethyl methyl carbonate, 1 part of inorganic conductive lithium salt and 1 part ofadditive benzonitrile. The high voltage performance can be improved by adding the benzonitrile additive, a dense and uniform low-impedance protective film can be formed on the surface of a positive electrode material during battery cycling, and the protective film can inhibit the oxidative decomposition of the electrolyte solvent and can maintain the structural stability of the positive electrodematerial. The high voltage electrolyte is reliable in effect; the high-voltage functional additive benzonitrile is added into the electrolyte, so that the stability of a lithium ion battery is improved under high voltage; the method is simple, the operation is simple, the addition amount is small, and the high voltage electrolyte is practical and economical.

Description

technical field [0001] The invention relates to a lithium battery high-voltage electrolyte, in particular to a high-voltage electrolyte containing a benzonitrile additive and a preparation method thereof. Background technique [0002] The energy issue is one of the major issues facing mankind in the 21st century, and it has received great attention from all countries in the world. As an emerging new energy source, lithium-ion batteries are developing rapidly. Because of the characteristics of high energy density, high cut-off voltage and long cycle life, it has good commercial prospects. Common commercial lithium-ion cathode materials include lithium iron phosphate, lithium cobalt oxide, and nickel-cobalt-manganese ternary materials. Although the theoretical capacity of various positive electrode materials is relatively large, because the cut-off voltage does not exceed 4.2V, the energy density cannot be maximized. Increasing the cut-off voltage of positive electrode mat...

AI Technical Summary

Problems solved by technology

Although the theoretical capacity of various positive electrode materials is relatively large, because the cut-off voltage does not exceed 4.2V, the energy density cannot be maximized. Increasing the cut-off voltage of positive electrode materials is also facing new problems. As the voltage increases, the material structure The stability of the battery is reduced, and the incompatibility of the conventional electrolyte at high voltage leads to a decrease in the cycle performance of the battery

Commonly used carbonate-based electrolytes are prone to oxidative decomposition under high voltage, and the by-products produced have a negative impact on battery performance. On the one hand, the internal impedance of the battery increases, and on the other hand, the positive electrode material of the battery will also be corroded.

Especially for ternary materials, under high voltage, nickel-cobalt-manganese plasma will dissolve from the positive electrode material, causing the structure of the positive electrode material to collapse, resulting in irreversible attenuation of capacity, which will easily cause the performance of ordinary lithium battery materials to decay too quickly under high voltage. The problem of poor stability under voltage