Gallium doping induces enhanced cyclic stability and rate capacity of lithium-ion battery silicon anode

Abstract

Improving the long-term cyclic stability and rate capacity is key to the commercial application of the lithium-ion battery Si anodes. However, the severe volume expansion and low conductivity limit the electrochemical performance. This work reports a gallium (Ga) doping strategy to improve the long-term cyclic stability and rate capacity. Highly crystalline and uniform grain-sized Ga-doped Si nanoparticles are obtained through the molten salt process. It not only shows significantly increased conductivity (resistance reduced by 5.4-fold), but also presents a faster diffusion coefficient. Furthermore, the optimized electrode delivers a high initial discharge capacity of 2715 mAh g⁻¹ with an initial Coulombic efficiency of 89.12%. Additionally, the anode exhibits excellent rate capability; the high-rate capabilities of 2826 mAh g⁻¹, 2169 mAh g⁻¹, 1606 mAh g⁻¹, 1016 mAh g⁻¹, and 404 mAh g⁻¹ are obtained at the current density of 0.1 A g⁻¹, 0.5 A g⁻¹, 1 A g⁻¹, 2 A g⁻¹, and 5 A g⁻¹, respectively. Moreover, as the current density is restored to 0.1 A g⁻¹, the capacity recovered to 2035 mAh g⁻¹, which represents 72% of the initial reversible capacity. This work not only demonstrates that Ga can serve as a promising dopant for enhancing the long-cycle and rate performance of silicon-based anodes, but also underscores the significance of lattice dynamics and electronic structure tuning in the design of high-performance silicon anodes.