A kind of lithium ion battery electrolyte and lithium ion battery

Abstract

The invention discloses an electrolyte solution for a lithium ion secondary battery, which includes lithium salt, an organic solvent, additive A, and additive B. The molecular formula of the additive A is as follows: the molecular formula of the additive B is as follows: the additive A in the electrolyte, Reduce the viscosity of the electrolyte, improve the low-temperature conductivity, widen the temperature window range, and increase the lithium ion transfer rate of the electrolyte at low temperature; Additive B is conducive to the formation of a dense and stable SEI film on the surface of the negative electrode, thereby optimizing the electrode‑ The interface performance of the electrolyte; the synergy between the two can effectively improve the low-temperature cycle performance and storage performance of the battery.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to an electrolyte solution for lithium ion batteries. Background technique [0002] With its advantages of high specific energy, long cycle life, no memory effect, safety and reliability, and fast charging and discharging, lithium-ion batteries have become a bright spot in the research of new energy power supply technology. At present, they have been widely used in portable electronic products, and gradually Occupy the new energy vehicle power supply market. However, such a lithium-ion battery with such excellent performance is very sensitive to temperature. Low temperature will lead to a decrease in the electrical performance of the lithium-ion battery, and even make the lithium-ion battery unusable. Low-temperature charging will even lead to the generation of lithium dendrites. In order to improve the low-temperature performance of lithium-ion batteries, a large num...

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Problems solved by technology

However, such a lithium-ion battery with such excellent performance is very sensitive to temperature. Low temperature will lead to a decrease in the electrical performance of the lithium-ion battery, and even make the lithium-ion battery unusable. Low-temperature charging will even lead to the generation of lithium dendrites.

In order to improve the low-temperature performance of lithium-ion batteries, a large number of scientific researchers have proposed various measures, such as the amorphous electrolyte technology proposed by Marta Kasprzyk of the Warsaw University of Technology, which extends the use temperature of the electrolyte to -60 ° C, Shanghai The ethyl acetate-based electrolyte proposed by Professor Xia Yongyao of the University further reduces the operating temperature of batteries with special materials to -75°C. The key to improving the low-temperature performance of lithium-ion batteries lies in the improvement of low-temperature performance of the electrolyte. Conventional commercial lithium-ion The viscosity of battery electrolyte will increase rapidly at low temperature, and the conductivity will drop sharply. Taking LB303, a common commercial lithium-ion battery electrolyte, as an example, its ion conductivity is about 10mS / cm at room temperature, but at -40°C, its The conductivity drops sharply to 0.02mS / cm, which seriously affects the low-temperature discharge performance of lithium-ion batteries. Therefore, the key to improving the low-temperature performance of lithium-ion batteries is to improve the low-temperature performance of the electrolyte

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