Constituents of electrolyte of lithium ion battery possessing function of guarding against over charge, and gaseous distention

Abstract

The composition of electrolyte includes ethylene carbonate, methyl ethyl carbonate, diethyl carbonate, cyclohexyl benzene, vinylene carbonate, 1,3 - propane sultones, and lithium phosphofluoric acid. When overcharge occurs in battery, electric polyreaction takes place in the disclosed electrolyte, and polymerization membrane is generated at surface of electrode to make internal resistance of battery increase rapidly so as to prevent battery from overcharging further, and prevent explosion of battery from occurring effectively. At the same time, stable passive film on battery is formed in reduction procedure so as to make battery possess better storage capability.

Description

technical field [0001] The invention relates to a lithium-ion battery electrolyte, in particular to a composition of the lithium-ion battery electrolyte with anti-overcharge and anti-flat. Background technique [0002] At present, the production of small-capacity lithium-ion batteries in the 3C industry, such as mobile phone batteries and laptop batteries, has basically become saturated, but large-capacity power lithium-ion batteries have still not entered the market. Lead-acid batteries still dominate the application fields of electric vehicles and large mobile power supplies. The positive electrode materials of lithium ion batteries are usually lithium cobaltate, lithium manganate or lithium nickelate and various transition metal oxides doped with other elements. The operating voltage of the lithium-ion battery is in the range of 3.0V-4.2V, and the rated voltage is 3.6V-3.7V. It uses carbonate mixed solvents (such as ethylene carbonate, propylene carbonate, dimethyl carb...

AI Technical Summary

Problems solved by technology

[0004] Furthermore, when the battery is overcharged, the high potential of the electrode (>4.3V, vsLi / Li+) is likely to cause the decomposition of the solvent, and the reaction will increase the temperature of the battery, causing the vapor pressure of the solvent to rise, thereby increasing the internal capacity of the battery. This is the direct cause of battery safety problems. Therefore, an effective way to improve battery safety performance in current technology is to increase the decomposition voltage and boiling point of the solvent in the battery electrolyte. The solvent used in the electrolyte has diethoxyethylene Alkanes, 1,3-dioxolane, ether, tetrahydrofuran, 2-methyltetrahydrofuran, methyl formate, methyl acetate, etc. have not been used because of their low boiling point or low decomposition voltage. At present, the electrolyte is generally used The solvent used is a mixed solvent of various carbonates. Due to the different properties of various carbonates, some studies believe that adjusting the content of the solvent in the electrolyte can improve the overcharge safety of the battery. Propylene carbonate (PC) and diethyl carbonate Esters (DEC) can be embedded in the graphite negative electrode and decompose during the charge and discharge process. If the content of PC and DEC in the electrolyte is reduced, or an appropriate solvent ratio is used, the safety performance of the battery can be improved