Study On Electrolyte of Low Temperature Sodium-Ion Battery

Abstract

With the rapid development of electronic devices, energy storage systems with excellent performance are required. To be used in cold climates and high-altitude areas, it is required that the battery should work stably and operate safely even when the temperature drops below freezing point. Sodium-ion batteries arouse great attention, because of their high safety, good capacity in both high and low-temperature environments, along with their abundant sodium resources in the earth's crust. But for practical applications, the kinetics of sodium-ion batteries become slow when working at low temperatures. The performance deteriorates with the temperature decreases. Therefore, researchers have carried out a lot of research to overcome these problems in the low-temperature environment. For example, the energy storage performance of sodium-ion batteries can be improved by optimizing the positive and negative electrodes, separators, and electrolytes. Among them, optimizing the electrolyte is critical to improving the energy storage performance of sodium-ion batteries. Because the electrolyte is an important part, which is in contact with each part of the battery as a medium, which is mainly composed of solvents, electrolyte salts, and additives. During the charge/discharge processes of the battery, the electrolyte plays a role to act as an ionic conductor to transfer Na + between the positive and negative electrodes and link then together. Additionally, the electrolyte will also directly participate in the reaction on the electrode surface and form SEI film. Thus, it is one of the most economical and effective means to enhance the low-temperature performance by modifying the electrolyte. This paper, summarizing the reports on the electrolyte of low-temperature sodium-ion batteries at home and abroad, sorting out and analyzing the solid, liquid, and gel electrolytes, clarifies how to making the electrochemical performance of sodium-ion batteries better by optimizing electrolytes.