Sn@Zn/Co-NPC as Anode Materials for Sodium-Ion Batteries via the Solvothermal Method

Sodium-ion batteries are considered promising for large-scale energy storage due to their abundance. Therefore, it is crucial to develop stable anode materials with high specific capacity. SnO₂ was coated with Zn/Co-zeolitic imidazolate frameworks (ZIFs) by using the solvothermal method to obtain SnO₂@Zn/Co-ZIFs. Then, Sn@Zn/Co-NPC (N-doped porous carbon) was obtained through heat treatment in an inert atmosphere. In this material, Sn provides a higher capacity, while Zn/Co-NPC not only can provide part of the capacity and increase the conductivity of the material, but also helps alleviate the volume expansion of Sn during the charge and discharge process. Therefore, the effect of the amount of Sn on the electrochemical properties of the materials was investigated by varying the addition of SnO₂. The results show that the 50Sn@Zn/Co-NPC electrode material retains a discharge specific capacity of 334.90 mAh g⁻¹ after 100 cycles at 100 mA g⁻¹ current density. After 200 cycles at 500 mA g⁻¹ current density, 50Sn@Zn/Co-NPC electrode material still has 275.80 mAh g⁻¹ discharge specific capacity. The 50Sn@Zn/Co-NPC electrode material has excellent electrochemical properties. Therefore, this paper provides a reference for the design of stable, long-cycle, and low-cost anode materials for sodium-ion batteries.