Binder-free rGO–Si composite anodes with controlled silicon content and composition-dependent electrochemical performance

Abstract

Silicon is a promising anode material for lithium-ion batteries due to its extremely high theoretical capacity, yet its practical implementation is hindered by severe volume expansion and interfacial instability during cycling. In this work, binder-free reduced graphene oxide-silicon (rGO–Si) composite anodes with systematically controlled silicon contents (25–75 wt%) are fabricated to elucidate the role of composition in governing electrochemical behavior. The rGO framework forms a continuous conductive network and a mechanically compliant matrix, facilitating more uniform silicon dispersion and buffering volume changes. Electrochemical measurements reveal that the rGO–Si composite containing 75 wt% silicon delivers the best overall electrochemical performance among the investigated compositions, achieving a reversible capacity of ∼1150 mA h g⁻¹ at 0.5 A g⁻¹ with ∼90% capacity retention after 100 cycles. Thermogravimetric analysis confirms the compositional robustness and enhanced thermal stability of the composite structure, while electrochemical impedance spectroscopy demonstrates reduced charge-transfer resistance and improved interfacial kinetics compared with pristine silicon. These results highlight the critical role of compositional optimization in rGO–Si composite anodes and provide a practical strategy for developing durable and high-performance silicon-based anodes for next-generation lithium-ion batteries.