A bicomponent electrolyte additive towards stabilized interface for high-performance lithium-ion batteries

A good electrode interface film is the guarantee for the efficient migration of lithium-ions (Li-ions) between the cathode and anode and is also the basis for achieving a stable cycle of high-specific energy secondary batteries. However, the cathode electrolyte interface (CEI) and solid electrolyte interface (SEI) formed on the surface of the cathode and anode via the commonly used electrolyte do not have good interface stability and excellent performance. Pouch cells with NCM523/graphite cycle with conventional electrolytes fell below 20% capacity retention in under 150 cycles. Herein, we employ a bicomponent lithium difluorophosphate (LiPO2F2) and ethylene sulfate (DTD) electrolyte additive to enhance the stability of the interface film. According to theoretical calculation results, LiPO2F2 is easier to oxidize and decompose on the surface of the cathode and DTD is more likely to undergo reductive decomposition on the anode surface than other solvents. When matched with a 5000mAh NCM523/graphite pouch cell, the new electrolyte additive can effectively improve the electrode interface stability and the cycling performance (almost 100% capacity retention after 200 cycles) under severe cycling conditions. Overall, this work offers new fundamental insights into the interface optimization and provides direction for the design of new electrolyte additive to better stabilize the lithium-ion batteries (LIBs).

Automated summary

This work enhances the stability of the electrode interface film by using a new electrolyte additive, thereby improving the cycling performance of lithium-ion batteries.