Preparation of Sn/Zn/Co-NPC composite anode materials via impregnation method for sodium-ion batteries with enhanced cycling stability

Bimetallic zeolitic imidazolate framework materials (Zn/Co-ZIFs) represent a notable class within the field of metal–organic frameworks (MOFs). These materials are characterized by their advantageous properties typical of MOFs, including a high specific surface area and tunable pore sizes, in addition to exhibiting the structural stability that is characteristic of zeolites. In contrast, although tin-based materials demonstrate a high theoretical specific capacity, they experience significant volume changes during the charge and discharge cycles of batteries, leading to materal degradation and reduced cycling stability. In this study, Sn doping was successfully achieved in Zn/Co-NPC (N-doped porous carbon) by thermally treating Zn/Co-ZIFs at 700℃ through an impregnation method. This doping enhanced the sodium storage capacity of Zn/Co-NPC and improved its electrochemical performance. Experimental data indicate that the Sn/Zn/Co-NPC composite has a specific surface area of 332.80 m² g⁻¹ and an average pore diameter of 7.30 nm. When this composite is used as the anode material in sodium-ion batteries, it demonstrates outstanding performance: after 100 cycles, its reversible specific capacity reaches 344.20 mAh g⁻¹ (at a current density of 100 mA g⁻¹) and exhibits excellent rate capability. Consequently, this study provides substantial insight into the prospective advancement of structurally stable and high-capacity anode materials for sodium-ion batteries.