A High Voltage Magnesium Ion Battery Based on Na₃V₂(PO₄)₃@C Cathode and Bi Nanowire Anode

With the growing demand for green energy storage, magnesium batteries have emerged as a promising technology due to their low cost and superior theoretical capacity. This study optimizes the magnesium storage performance of Na₃V₂(PO₄)₃ and Bi through two strategies: uniform carbon coating and nanostructural design, respectively. Building on this, a full magnesium battery was constructed using Na₃V₂(PO₄)₃@C as the high-voltage cathode material and Bi nanowires as the anode, with Mg(TFSI)₂/AN electrolyte, and its electrochemical performance was thoroughly investigated. Electrochemical tests reveal that the full cell exhibits a high-voltage reaction plateau at 2.7 V/2.2 V. The initial discharge capacity of the full cell is 76 mAh/g, which maintains 62 mAh/g after 100 cycles, corresponding to a capacity retention of 82%, indicating outstanding cycling stability. Furthermore, at a high rate of 500 mA/g, the magnesium battery retains a discharge capacity of approximately 45 mAh/g, showcasing its excellent rate capability. This study provides insights for the realization of high-voltage, high-capacity, and long-cycle stability in magnesium batteries, advancing the technology toward higher energy densities and extended service lifetimes.