Electrolyte and preparation method as well as secondary lithium-sulfur battery using electrolyte

Abstract

The invention discloses electrolyte and a preparation method as well as a secondary lithium-sulfur battery using the electrolyte. The electrolyte is prepared from lithium salt, an organic solvent anda functional additive, wherein the concentration of the lithium salt in the electrolyte is 0.5 to 5 mol/L, and the mass percentage of the functional additive in the electrolyte is 0.1 to 3 percent. The electrolyte is prepared by adding the lithium salt into the organic solvent and uniformly stirring the lithium salt and the organic solvent, and functional electrolyte for the secondary lithium-sulfur battery is obtained by adding the functional additive into the electrolyte and continuously stirring the components till the components are uniformly mixed. The electrolyte disclosed by the invention takes trifluoropentaphenyl borane as the functional additive which can participate in formation of a solid electrolyte phase interface (an SEI film), and can dissolve LiF to improve the conductivity of the SEI film; the trifluoropentaphenyl borane is favorable for promoting dissociation reaction of LiPF6 to adsorb free F<->, so that HF formed by trace water is reduced, and corrosion of the HF to an electrode material is reduced; capacity attenuation of a cathode material in a cyclic process is effectively suppressed, and the cycle stability and the capacity retention rate of the lithium-sulfur battery are improved.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to an electrolyte, a preparation method and a secondary lithium-sulfur battery using the electrolyte. Background technique [0002] In recent years, lithium-ion batteries have been widely used in mobile electronic devices and electric vehicles due to their advantages of high mass energy density and volumetric energy density. However, with the rapid development of electric vehicles, the performance requirements for lithium-ion batteries are gradually increasing. Lithium-sulfur secondary batteries have high energy density. Lithium-sulfur batteries using sulfur element or sulfur-containing substances as positive electrode active materials have a theoretical specific energy of 2600Wh·kg -1 . In addition, the lithium-sulfur battery also has the advantages of rich sulfur resources, low price, environmental protection and no pollution, and is a very promising battery. [0003]...

AI Technical Summary

Problems solved by technology

At present, the solution to the above problems is mainly to design the structure of the positive electrode material to improve the performance, and to use lithium nitrate as the negative electrode additive of the electrolyte. The effect is obvious but not ideal.

Positive electrode film-forming additives play an important role in improving the performance of lithium-sulfur batteries. At present, there are few studies on positive electrode film-forming additives.

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