High-security phosphate-based electrolyte and lithium ion battery

Abstract

The invention relates to a phosphate-based electrolyte and a lithium ion battery. The electrolyte is mainly characterized by taking at least one cyclic phosphate and at least one chain phosphate as solvent components. The advantages of the phosphate-based electrolyte are that: the two kinds of phosphates both have a flame retardation characteristic, and the cyclic phosphate can be subjected to ring-opening polymerisation under abuse conditions of high temperature, over charge or the like, and the electrolyte is gelated, the internal resistance of a battery increases, and therefore the battery security is improved. The cyclic phosphate can form into membranes on an anode surface and a cathode surface of the lithium ion battery, and improves the compatibility between the electrolyte, and the anode and the cathode; the usage of the chain phosphate helps to reduce the electrolyte viscosity and improve the electrolyte conductivity, and good multiplying power performance and low temperature performance are provided in the corresponding battery system. The security of the lithium ion battery can be improved substantially by using the electrolyte.

Description

technical field [0001] The invention relates to a phosphate-based electrolyte and a lithium-ion battery thereof, in particular to a high-safety electrolyte with cyclic phosphate and chain phosphate as a mixed solvent, belonging to the technical field of electrochemical and chemical power supply products . Background technique [0002] Lithium-ion batteries have the advantages of high energy density, high working voltage, long cycle life, no memory effect, fast charging and discharging, etc., and have been widely used in portable electronic products such as mobile phones, notebook computers and small power-driven devices. At present, the electrolytes of lithium-ion batteries are mostly organic liquid electrolytes, which are composed of organic solvents and conductive lithium salts. Commonly used organic solvents are carbonate compounds, such as ethylene carbonate (EC), diethyl carbonate (DEC) and ethyl methyl carbonate (EMC). These carbonate-based electrolytes are also wide...

AI Technical Summary

Problems solved by technology

[0004] However, chain phosphate esters like TMP and DMMP mostly have the characteristics of poor compatibility with electrodes, especially with graphite negative electrodes. At lower potentials (about 1.3-0.9V vs. Li / Li + ), this type of chain phosphate will react with Li + Co-embedded between the graphite layers, and further reduced and decomposed, the graphite electrode was damaged by electrochemical stripping, which greatly increased the irreversible capacity of the graphite negative electrode and made it difficult to stabilize the cycle.

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