Electrolytic solution and lithium ion battery containing same

Abstract

The invention provides an electrolytic solution, which comprises an organic solvent, a lithium salt and a quick charge cycle improvement additive, wherein the organic solvent comprises ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate and ethyl propionate, the quick charge cycle improvement additive comprises vinylene carbonate and methylene methanedisulfonate, based on the total massof the electrolytic solution of 100%, the content of vinylene carbonate is 0.2-3%, and the content of methylene methanedisulfonate is 0.1-2%. The invention also provides a lithium ion battery containing the electrolytic solution. According to the invention, specific carbonic ester, carboxylic ester and the quick charge cycle improvement additive are screened and combined for use, so that the quick charge capacity of the lithium iron phosphate system lithium ion battery can be remarkably improved, the quick charge time is shortened, the low-temperature discharge power performance can be improved, the negative electrode graphite co-embedding phenomenon in the normal-temperature formation process of the lithium iron phosphate battery can be remarkably improved, and powder falling of the negative electrode is avoided so as to improve the cycle performance and the service life of the battery.

Description

technical field [0001] The invention belongs to the technical field of batteries, and in particular relates to an electrolyte and a lithium ion battery containing the electrolyte. Background technique [0002] Lithium iron phosphate batteries are widely used due to their advantages such as long cycle life, high safety, and fast charging. However, the current lithium-ion battery electrolyte suitable for the lithium iron phosphate system has the following disadvantages under the condition of high-rate fast charging of the battery: (1) The battery resistance and polarization are large, and it is difficult to shorten the fast charging time and improve the fast charging performance; ( 2) The viscosity of the low-temperature electrolyte system increases, which can easily lead to lithium precipitation under fast charging and high-rate cycle conditions, and the battery power performance is poor; (3) Lithium ions and solvent molecules are co-intercalated in the negative electrode car...

AI Technical Summary

Problems solved by technology

However, the current lithium-ion battery electrolyte suitable for the lithium iron phosphate system has the following disadvantages under the condition of high-rate fast charging of the battery: (1) The battery resistance and polarization are large, and it is difficult to shorten the fast charging time and improve the fast charging performance; ( 2) The viscosity of the low-temperature electrolyte system increases, which can easily lead to lithium precipitation under fast charging and high-rate cycle conditions, and the power performance of the battery is poor; (3) Lithium ions and solvent molecules are co-intercalated in the negative electrode carbon material during the normal temperature formation process of the battery. Solvent molecules entering the negative electrode material undergo oxidation-reduction reactions with the negative electrode material, generating stress that destroys the structure of the negative electrode carbon material. When graphite is used as the carbon material, the co-embedding phenomenon is the most serious, and the negative electrode will drop powder, and the cycle and storage performance will be significantly reduced.

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