Electrolyte adaptive to high-nickel ternary positive electrode material

Abstract

The invention relates to an electrolyte adaptive to a high-nickel ternary positive electrode material. The electrolyte comprises an electrolyte lithium salt, a non-aqueous organic solvent and additives, the additives comprise a positive electrode film-forming additive, a negative electrode film-forming additive and a flame-retardant additive, the positive electrode film-forming additive is sodiumdihydrogen phosphate, the negative electrode film-forming additive is p-toluenesulfonyl isocyanate, and the flame-retardant additive is (trifluoroethoxy) pentafluorocyclotriphosphazene. According to the electrolyte adaptive to the high-nickel ternary positive electrode material, the normal-temperature/high-temperature circulation, high-temperature storage and safety performance of a high-nickel ternary positive electrode material battery under high voltage are effectively improved through a synergistic effect generated by combined use of multiple additives.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion battery electrolytes, and in particular relates to an electrolyte suitable for high-nickel ternary positive electrode materials. Background technique [0002] In recent years, high-nickel ternary layered oxides (LiNi x mn y co z o 2 , x≥0.6, x+y+z=1, high-nickel NCM) is considered to be one of the hotspots in the development of cathode materials for next-generation high-energy-density lithium-ion power batteries. However, due to the influence of Li-Ni mixed discharge, phase transition reaction, gas production, microcracks, transition metal dissolution, and surface structure, it suffers severe capacity fading during long cycle, which hinders the large-scale application of high-nickel NCM. To improve the stability of high-nickel NCMs, common modification methods include coating, doping, and the development of electrolyte additives. The coating can prevent the occurrence of side reactions be...

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Problems solved by technology

[0003] High nickel NCM can obtain more specific capacity under high temperature and high pressure, but it is also easy to accelerate the oxidative decomposition of the electrolyte and the side reaction between the electrode / electrolyte, and lead to the deterioration of the battery cycle stability and safety performance

First, the electrolyte oxidation on the surface of the high-nickel NCM positive electrode generates soluble acidic substances, which will migrate to the negative electrode, causing acid-induced damage to the solid electrolyte interphase (SEI) of the negative electrode, which in turn causes cycle capacity decay; secondly, the continuously growing lithium during the cycle Dendrites can also cause problems such as short circuits, fires and explosions in batteries

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