Electrolyte containing silicon solvent and pyridine additive and lithium ion battery applying electrolyte

Abstract

The invention discloses an electrolyte containing a silicon solvent and a pyridine additive and a lithium ion battery applying the electrolyte. The electrolyte contains lithium salt, an organic solvent and an additive, wherein the organic solvent includes a silicon-substituted organic solvent, the additive includes a nitrile-group-containing pyridyl compound, the organic solvent can also include one or more of a chain carbonate ester organic solvent, a cyclic carbonate ester organic solvent. According to the invention, an electrolyte membrane with conductivity is formed on the surface of the positive electrode by using the nitrile-group-containing pyridyl compound so as to inhibit metal dissolution, the content of HF is reduced by complexation with HF in the electrolyte, the corrosion effect of HF on the positive electrode material is reduced, and the cycle life and capacity retention rate of the battery are finally improved; and meanwhile, the viscosity of the electrolyte is reduced while protecting the positive electrode through adding the silicon-substituted organic solvent, the electrode interface is optimized, the increase of impedance is restrained, and the low temperature and rate performance of the battery are guaranteed.

Description

technical field [0001] The invention relates to the field of batteries, in particular to an electrolyte containing a silicon solvent and a pyridine additive and a lithium ion battery using the electrolyte. Background technique [0002] With the increase of electric vehicles, cordless power tools and military applications, the energy density of lithium-ion batteries has increased to higher requirements. At present, it is mainly by selecting high-capacity, high-compression positive and negative active materials and increasing the charge cut-off potential of positive active materials. However, the latter will increase the oxidation activity of the positive electrode, intensify the oxidative decomposition of the electrolyte, and reduce the overall performance of the battery. When lithium ions are in a high-temperature state such as heat exposure and continuous discharge heat, the damage to the active material will be accelerated and the battery will also produce a large amount ...

AI Technical Summary

Problems solved by technology

In a high-voltage environment, a large number of lithium ions in the positive electrode material will be extracted, which will affect the safety performance and cycle stability of the battery.

[0003] At present, LiPF is the most widely used electrolyte lithium salt in lithium-ion batteries. 6 , its advantage is that it has good electrical conductivity, wide electrochemical window, and good high and low temperature performance; however, LiPF 6 The disadvantage is that it is sensitive to water and thermally unstable. It is easy to decompose and produce HF in the presence of trace water or at a higher temperature, and the existence of HF will damage the SEI film and electrode materials, eventually resulting in the reduction of battery capacity and the destruction of battery performance.

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