Tailored electrolyte additive design for suppressing irreversibility in dry-processed anodes and enhancing electrochemical stability in full-cells

초록

Introducing silicone (Si) with high theoretical capacity into dry electrode technology offers potential to dramatically boost the energy density of lithium-ion batteries (LIBs), making them an attractive candidate for next-generation high-energy storage systems for electric vehicles (EVs). However, the continuous volume expansion/contraction of Si during cycling and the irreversible decomposition of polytetrafluoroethylene (PTFE) in the reduction process significantly degrade the interfacial and mechanical stabilities of Si-based dry-processed anodes during cycling. In this study, we introduced fluoroethylene carbonate (FEC) as an electrolyte additive to address these challenges in a dry-processed Si/C–graphite composite (DSG) anode system. This strategy effectively suppressed PTFE decomposition by facilitating the formation of a stable LiF-based solid electrolyte interphase (SEI) layer and alleviated the volume change of DSG anode through improved mechanical properties. In addition, we systematically tailored the concentration of FEC to improve the electrochemical stability at both the anode and cathode while observing the distinct degradation mechanisms occurring at each electrode under excessive FEC addition conditions. The resulting balanced electrolyte additive design enabled a high-performance full-cell using a DSG anode with a high areal capacity of 7.6 mAh cm−2, leading to a high average coulombic efficiency (CE) of 99.9% and high areal capacity of 4.6 mAh cm−2 after 300 cycles. These insights into the DSG anode system offer a practical pathway toward high-energy-density LIBs.