Electrolyte and lithium battery

Abstract

The invention relates to an electrolyte. The electrolyte comprises an organic solvent, an electrolyte and an additive, wherein the additive comprises a coordination compound containing sulfone-boron trifluoride. By adding the coordination compound containing sulfone-boron trifluoride to the solvent of the electrolyte, the coordination compound containing sulfone-boron trifluoride can form a favorable interface film on the surface of a negative electrode of a lithium ion battery, the reaction activity of the surface of a positive electrode is simultaneously reduced, the electrolyte oxidation and decomposition on the surface of the positive electrode is inhibited, and the high-temperature storage performance and the cycle performance of a lithium ion secondary battery are improved.

Description

technical field [0001] The present application relates to the technical field of lithium-ion batteries, in particular to an electrolyte and a lithium-ion battery. Background technique [0002] Electronic mobile devices such as laptops, mobile phones, handheld game consoles, and tablet computers can achieve more and more functions, and the application technologies of electric vehicles and smart grids are becoming more and more mature. People have higher and higher requirements for the battery life of the lithium-ion secondary battery as its main driving energy. Improving energy density has become a research hotspot in lithium-ion secondary batteries. [0003] For lithium-ion secondary batteries whose cathode material is nickel-cobalt-manganese ternary material, increasing the charging cut-off voltage is an effective way to increase the energy density of the battery. However, when the voltage of the lithium-ion secondary battery is increased, especially when the charging vol...

AI Technical Summary

Problems solved by technology

However, when the voltage of the lithium-ion secondary battery is increased, especially when the charging voltage reaches above 4.35V, two phenomena will appear inside the battery: 1. Due to the increased delithiation ratio, the structural stability of the positive electrode material is reduced, and phase transition is prone to occur Reduce the capacity of the positive electrode; at the same time, the transition metal dissolves intensified, migrates to the negative electrode to destroy the SEI, produces a large amount of reducing gas, and consumes the electrolyte

2. Since the voltage has exceeded the redox window of the electrolyte, the electrolyte will undergo an oxidation reaction on the positive electrode, rapidly consume the electrolyte, and produce a large amount of by-products or gases

In actual use, electronic products are also faced with continuous use of heat or an increase in the ambient temperature of the lithium-ion secondary battery, which may cause the lithium-ion secondary battery to be in a high temperature state, and at high temperature, the electrolyte will be subject to stricter conditions. In severe cases, due to the expansion and deformation of the lithium-ion secondary battery, a short circuit occurs inside the lithium-ion secondary battery or the packaging of the lithium-ion secondary battery bursts, resulting in the leakage of flammable electrolyte, causing fire and other safety accidents

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