Efficient synthesis of high areal capacity Si@graphite@SiC composite anode material via one-step electro-deoxidation

Abstract

Although Si is a promising anode material for lithium-ion batteries, scalable synthesis of Si anodes with high cyclability and low swelling remains a significant challenge. Herein, we describe the electrochemical fabrication of a Si@graphite@SiC composite anode from a SiO2/graphite mixture via an electro-deoxidation-based molten salt process. The exfoliated graphite enhances the electrical conductivity of the composite and cushions the volume expansion of Si nanowires, while the SiC component acts as an active matrix that accommodates the expansion of the Si during lithiation. This significantly increases the electrode cycle life. In half-cell testing, the composite exhibited 80% capacity retention until 500 cycles. It showed good cycling performance even at a high areal capacity of 4.6 mAh/cm2. Further, a full cell comprising the composite anode and a LiNi0.6Co0.2Mn0.2O2 cathode possessed a high capacity and demonstrated 84% capacity retention after 70 cycles. This work provides new insights into the rational design of alloy anodes for high-energy density batteries.