Phosphorus-doped silicon copper alloy composites as high-performance anode materials for lithium-ion batteries

Silicon (Si) anodes are considered one of the most promising candidates for next-generation lithium-ion batteries, owing to their high theoretical capacity. However, Si-based anodes suffer from significant volume expansion during lithiation, leading to severe mechanical degradation and poor cycling stability. To address these challenges, We developed phosphorus (P)-doped Si-Cu alloy composites via a simple vacuum melting method. The incorporation of Cu3Si in the composites effectively suppressed the volume expansion of Si, while P doping enabled the formation of N-type Si to improve electrical conductivity. In our study, we conducted a comprehensive analysis of the electrochemical performance of the P-doped Si-Cu alloy composites. Among the samples, the P0.5% Si-Cu alloy composite exhibited the most exceptional electrochemical performance, with a capacity of 1048 mAh/g after 60 cycles at the current density of 100 mA/g. Electrochemical impedance spectroscopy (EIS) measurements revealed a lower Rct value of 73.65 Ω for the P0.5% Si-Cu alloy composite compared to 175.2 Ω for the Si-Cu alloy composite. Our theoretical calculations also demonstrated that P doping reduces the energy barrier for lithium-ion diffusion. Our study validated the potential of P-doped Si-Cu alloy composites as high-performance anode materials for lithium-ion batteries and provides new insights into the design of Si-based anodes with improved stability and cycling performance.