Electrolyte solution of lithium ion battery

Abstract

The invention discloses electrolyte solution of a lithium ion battery, and aims to provide electrolyte solution of a lithium ion battery with high discharging performance and larger operating temperature windows. The electrolyte solution of the lithium ion battery comprises a solvent and lithium salt, wherein the solvent comprises 60 to 90 weight percent of cyclic carboxylic ester gamma-butyrolactone and 10 to 40 weight percent of linear carboxylic ester. The cyclic carboxylic ester gamma-butyrolactone solvent has a low melting point, a high boiling point and lower viscosity, can expand the temperature window of the electrolyte solution, improves the high-temperature and low-temperature performance of the electrolyte solution and improves the discharging performance of the lithium ion battery, so that the lithium ion battery can be operated in an environment at the temperature of between -40 and 50 DEG C; therefore, the battery has the high discharging performance and the larger operating temperature windows.

Description

technical field [0001] The invention relates to a lithium ion battery electrolyte. Background technique [0002] Lithium-ion batteries were commercialized in the 1990s. With the continuous development and innovation of technology, relevant scientific and technological personnel are constantly improving the electrochemical performance and safety performance of lithium-ion batteries under harsh conditions, in order to expand their application fields. Among them, the ability to take into account the performance under high and low temperatures has always been one of the focuses of people's research and development. The usual situation is that a battery with good battery performance at room temperature can only be used at low temperature or at high temperature, but it cannot be used at the same time. The main reason is that the temperature window of the lithium-ion battery electrolyte is too narrow to take into account both high and low temperature performance. The main reasons...

AI Technical Summary

Problems solved by technology

Among them, from the perspective of the temperature window, propylene carbonate has a low melting point and a high boiling point, and is the first choice for cyclic carbonate solvents. However, in actual use, it is found that propylene carbonate will cause the carbon negative electrode material to peel off. Lead to serious degradation of battery performance; ethylene carbonate has a relatively high melting point (39°C), and when the temperature is low, ethylene carbonate will first solidify and precipitate, so its effect is not good when used at low temperatures

In the electrolyte, the dielectric constant of the cyclic ester solvent is relatively high, and it has a good dissociation effect on the electrolyte salt, so its role in the electrolyte is indispensable, but due to the above reasons, the limitation In addition, this type of solvent is the main solvent in the electrolyte. Therefore, in order to change the temperature window of the electrolyte, it is necessary to find a new solvent with a higher dielectric constant and a wider temperature window to compensate for the cyclic carbonate solvent. lack of

[0003] In the patent CN200510107424.9, γ-butyrolactone with a volume ratio of 1%-50% is added to improve the high temperature and low temperature performance of the electrolyte, but there are still more than 40% of cyclic carbonate and linear carbonate solvents , from the perspective of solvent composition, it still faces the problem of low-temperature solvent precipitation, and the purpose of this patent is mainly to add a certain amount of additives to improve the wettability of the electrolyte. The article does not make specific details on the high and low temperature performance of the electrolyte. Explain that the patent CN200710123621.9 provides a lithium battery electrolyte with good high temperature stability. This system uses more than 40% of cyclic carbonate solvents. It is obvious that its high temperature performance will be slightly better, but it can be seen from the above that its low temperature The performance will be very poor. Patent CN200910115382.1 provides a low-temperature electrolyte for power lithium-ion batteries. This system also uses a large amount of carbonate solvents, which shows that its low-temperature performance is also limited.

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