Additives to propylene carbonate-based electrolytes for lithium-ion capacitors

Nowadays, lithium-ion capacitors (LICs) have become a type of important electrochemical energy storage devices due to their high power and long cycle life characteristics with fast response time. As one of the essential components of LICs, the electrolytes not only provide the anions and cations required during charge and discharge processes, but also supply the liquid environment for ions to migrate between anodes and cathodes in LIC cells. It is well accepted that propylene carbonate (PC) cannot be used as a single solvent for Li-ion electrolyte due to the failure to form stable SEI film on graphite surface. In this work, the compatibility of PC-based electrolyte with commercial soft carbon anode and activated carbon cathode has been validated by using the laminated pouch LIC cells. The effects of additives on the electrochemical properties of PC-based LICs have been systematically investigated. Ethylene sulfite (ES) was proved to be an effective additive to promote capacity retention at high C-rate, which is superior to vinylene carbonate and fluoroethylene carbonate. The addition of 5 wt% ES plays an important role in reducing internal resistance, as well as improving electrochemical stability and low-temperature performances. This study is expected to be beneficial to explore robust electrolyte/additive combinations for LICs to reduce the internal resistance and to improve the low-temperature performances.

Automated summary

Nowadays, lithium-ion capacitors (LICs) have become important electrochemical energy storage devices due to their high power and long cycle life characteristics. The compatibility of propylene carbonate (PC)-based electrolyte with commercial carbon anode and activated carbon cathode in LICs has been validated in this study. The effects of additives on PC-based LICs' electrochemical properties have been investigated, and ethylene sulfite has been proven to be an effective additive for capacity retention.