Lithium iron phosphate long-life battery electrolyte for energy storage

Abstract

The invention discloses a lithium iron phosphate long-life battery electrolyte for energy storage. The main components of the electrolyte are as follows: a lithium salt, an organic solvent and a composite synergistic film-forming additive, wherein the lithium salt of the electrolyte is lithium hexafluorophosphate, lithium difluorooxalate borate, lithium perchlorate, lithium tetrafluoroborate and the like, and the organic solvent comprises cyclic carbonate and chain carbonate. On the basis of a conventional negative electrode film-forming additive, a positive electrode CEI film-forming additiveand a reinforced CEI film and SEI film passivation additive are added, so that the SEI film can stably exist under the conditions of normal temperature and high temperature, the reaction between theelectrolyte and a pole piece is reduced, the structures of the positive and negative electrode materials are more stable, and the cycle life under the conditions of normal temperature and high temperature is prolonged. When the electrolyte is applied to a lithium ion battery, the normal-temperature and high-temperature cycle life of the battery can be prolonged, and the national standard electrical performance and safety performance are completely met.

Description

technical field [0001] The invention relates to the field of electrochemistry, in particular to an electrolyte solution for lithium iron phosphate long-life battery for energy storage. Background technique [0002] The cycle performance of lithium-ion batteries is an important performance index for investigating batteries. At present, from the perspective of the electrolyte, the existing technical solution to improve the battery cycle performance is to add only a single negative electrode film-forming additive to the electrolyte, so that a layer of SEI protective film is formed on the negative electrode during the battery cycle to reduce electrolysis. The side reaction between the liquid and the negative electrode, but because the positive electrode does not form a protective film or the formed positive and negative protective film is not dense enough, the side reaction between the positive and negative electrode materials and the electrolyte increases, resulting in a decrea...

AI Technical Summary

Problems solved by technology

At present, from the perspective of the electrolyte, the existing technical solution to improve the battery cycle performance is to add only a single negative electrode film-forming additive to the electrolyte, so that a layer of SEI protective film is formed on the negative electrode during the battery cycle to reduce electrolysis. The side reaction between the liquid and the negative electrode, but because the positive electrode does not form a protective film or the formed positive and negative electrode protective film is not dense enough, the side reaction between the positive and negative electrode materials and the electrolyte increases, resulting in a decrease in cycle performance and shortened battery life.

[0003] In the prior art, conventional commercial lithium iron phosphate battery electrolytes generally only add a negative electrode film-forming agent. During the cycle, due to the increase in side reactions between the positive and negative electrodes and the electrolyte, it is difficult to achieve 1C / 1C normal temperature cycle. More than 3500 times, capacity retention rate ≥ 80%, 1C / 1C45 ℃ high temperature cycle is difficult to achieve more than 2000 times, capacity retention rate ≥ 80%