A kind of electrolytic solution containing fluorine solvent and pyridine additive and lithium ion battery using the electrolytic solution

Abstract

The invention discloses an electrolyte for a fluorine-containing solvent and a pyridine additive and a lithium ion battery using the same. The electrolyte contains lithium salt, organic solvents and an additive. The organic solvents contain one or a plurality of fluorinated organic solvent, chain carbonate, cyclic carbonate and carboxylic acid ester, and the additive includes a pyridine compound containing a nitrile group. Compared with the conventional lithium ion battery not using the electrolyte, since the pyridine compound containing the nitrile group is added to the electrolyte and matched with the fluorinated organic solvent with better wettability, the electrode interface can be optimized. The impedance between the interfaces is reduced, and the low temperature performance is improved. At the same time, the property of an electrode / electrolyte interface film can be improved to inhibit the dissolution of the transition metal, the bloating speed of the battery under high temperature and high pressure is reduced, and the cycle life of the lithium ion battery under high temperature and high pressure can be prolonged.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to an electrolyte solution containing fluorine solvent and pyridine additives and a lithium ion battery using the electrolyte solution. Background technique [0002] At present, lithium-ion batteries are widely used in electric vehicles, power tools, aerospace and other fields due to their advantages such as high energy density, long cycle life, no memory effect, and environmental protection. With the attention of power tools, people have put forward higher requirements for the energy density, cycle performance, and high and low temperature performance of lithium-ion batteries. [0003] At present, the high-voltage cathode materials that have been reported include LiCoPO 4 、LiNiPO 4 and LiNi 0.5 mn 1.5 etc., its charging voltage platform is close to or higher than 5V, but the development of matching non-aqueous organic electrolytes lags behind high-voltage cathode materials,...

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Problems solved by technology

[0003] At present, the high-voltage cathode materials that have been reported include LiCoPO 4 、LiNiPO 4 and LiNi 0.5 mn 1.5 etc., whose charging voltage platform is close to or higher than 5V, but the development of matching non-aqueous organic electrolytes lags behind high-voltage cathode materials, which limits the application of lithium-ion secondary batteries

The conventional electrolyte is easy to decompose between the positive and negative electrodes of the battery, generating gas, which increases the internal pressure of the battery, and the internal temperature rises and becomes unstable, especially under the condition of high temperature and high pressure, the safety and cycle life of the battery are seriously affected

For example, the decomposition of H 2 O to make LiPF 6 / Carbonate electrolyte system undergoes self-catalytic reaction, and the intermediate product HF will lead to the dissolution of metal ions Mn and Ni in the positive electrode material, which will deteriorate the positive and negative electrode materials and reduce the battery capacity and cycle life.

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