Metal lithium-based secondary battery electrolyte and application thereof

Abstract

The invention provides a metal lithium-based secondary battery electrolyte and application thereof, and belongs to the technical field of electrolytes, and the metal lithium-based secondary battery electrolyte comprises a dioxo ring compound, a fluorine-containing solvent, a fluorine-free ether solvent, a fluorine-containing lithium salt and lithium nitrate. The fluorine-containing solvent is added into the electrolyte, so that the uniformity of interface current distribution is ensured, the deposition morphology of metal lithium is regulated and controlled, and the formation of dendritic crystals is inhibited; a dioxo ring compound is added to perform ring-opening polymerization reaction on the surface of the metal lithium to form an organic layer with certain elasticity, so that the deposition and dissolution coulombic efficiency of the metal lithium is improved; lithium nitrate is added and can cooperate with lithium fluoride to stabilize an interfacial film and improve the cycling stability; and by controlling the composition of the electrolyte, the deposition and dissolution coulombic efficiency of the metal lithium can be improved when the concentration of the fluorine-containing lithium salt is relatively low. The result of the embodiment shows that the first coulombic efficiency of the electrolyte provided by the invention reaches 92.3%, the coulombic efficiency can still be stabilized at 98.6% after 700 cycles, and the electrolyte has excellent cycle stability.

Description

technical field [0001] The invention relates to the technical field of electrolytes, in particular to an electrolyte for a metal lithium-based secondary battery and an application thereof. Background technique [0002] With the continuous development of portable electronic products and the rapid expansion of the electric vehicle market, the requirements for the energy density of the battery system are getting higher and higher, and the development of high-capacity, long-life anode materials is one of the important ways to increase its energy density. Lithium metal is a commonly used negative electrode material. However, for lithium metal, the Coulombic efficiency and safety issues caused by the lack of effective interface protection are still the main obstacles restricting its development. In response to this problem, researchers have known a variety of ways, among which the adjustment and design of the metal lithium interface film is the key to changing the deposition-diss...

AI Technical Summary

Problems solved by technology

However, in the prior art, it is usually necessary to add a high concentration of fluorine-containing lithium salt (above 7mol / L) to suppress dendrites, but an excessively high concentration of fluorine-containing lithium salt not only increases the cost of the electrolyte, but also increases the density of the electrolyte. Viscosity, reducing its electrochemical properties such as ionic conductivity

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