Method for preparing electrolyte for 5V lithium ion battery

Abstract

The invention discloses a method for preparing electrolyte for a 5V lithium ion battery. The method comprises the following steps of: 1) purifying and dehydrating sulfone and carbonic ester respectively and mixing to obtain a mixed solvent; 2) dissolving a lithium salt in the mixed solvent to obtain additive-free electrolyte; and 3) dissolving an additive in the additive-free electrolyte to obtain the electrolyte for the 5V lithium ion battery, wherein the additive is lithium difluoro(oxalato)borate (LiDFOB). The method has the advantages that: the electrolyte can improve the compatibility ofthe electrolyte and a high-voltage positive electrode, decomposition of the electrolyte on the surface of a high-voltage positive electrode material in a charging process can be reduced and a stable solid electrolyte interface (SEI) film on the surfaces of the positive electrode and a negative electrode is formed, so that charge and discharge capacity and cyclical stability of the positive electrode material are obviously improved; and the method is simple, easy to implement and low in raw material cost, has broad application prospect and is suitable for industrial production.

Description

technical field [0001] The invention relates to an electrolyte solution of a lithium ion battery, in particular to the preparation of an electrolyte solution suitable for a high voltage (5V) lithium ion battery. Background technique [0002] Lithium-ion batteries have been widely used in portable electronic devices such as mobile phones and notebook computers. The operating voltage of commercial lithium-ion batteries is 3.7 V, and the energy density is low, which cannot meet the development needs of portable electronic devices. Increasing the operating voltage of lithium-ion batteries is one of the effective ways to increase energy density. The high-voltage cathode materials that have been reported include LiCoPO 4 、LiNiPO 4 , Li 3 V 2 PO 4 、LiNi 0.5 mn 1.5 o 4 etc., its charging voltage platform is close to or higher than 5V, but there are few reports on the matching electrolyte. At present, the commonly used electrolyte of lithium-ion batteries is mainly 1M LiPF ...

AI Technical Summary

Problems solved by technology

Yin Zhenguo and others disclosed an electrolyte solution for improving the performance of lithium-ion batteries with lithium manganate as the positive electrode, which contains 0.1-0.5 mol / L lithium difluorooxalate borate as a film-forming additive, which can effectively inhibit the positive electrode of the battery and the electrolyte. Reaction slows down the fading of the capacity of the battery during cycling, but does not study the influence of difluorooxalate lithium borate on the performance of high-voltage positive electrode materials (CN 101350430A)

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