Abstract:

With the development of electric vehicles, portable applications and energy storage systems, high-performance lithium-ion batteries are urgently demanded, and the corresponding research becomes much more important. Electrolyte is one of the indispensable components for lithium-ion battery, resulting in a significant impact on the rate performance, temperature range, cycling performance, safety issue and so on. Lithium salt as the key component, is an important factor dominating the performance of the electrolyte. Various lithium salts and their solvation structures in the electrolyte evidently affect the quality of SEI layer derived from electrolytes and lithium ion migration behavior, leading to completely different electrochemical properties. The characteristics of different novel lithium salts are introduced in detail. Furthermore, the fact that a single lithium salt can’t meet all the required performance propels to design the high performance electrolyte with multi-salts. This electrolyte shows a series of advantages in expanding the working temperature range, suppressing the metal ion dissolution and improving the rate performance. Simultaneously, based on tuning the solvation structure of Li⁺ by increasing the concentration, a novel concentrated electrolyte is introduced, displaying the advantages such as the suppressed graphite peeling, the expanded electrochemical window, the suppressed Al corrosion, the improved metallic lithium plating/stripping and so on. Furthermore, detail discussion focuses on the mechanisms for the enhanced performance of the two excellent electrolytes. Finally, development tendency and application prospect of lithium-salt based electrolytes, especially these two novel electrolytes are discussed.

Key words: electrolyte, lithium salts, multi-salts electrolyte, concentrated electrolyte, review