Clozapine boosting N/Cl co-doped carbon skeleton synergistically optimizing Na₃V₂(PO₄)₃ with superior performance and excellent thermal stability

Nowadays, the limited electronic conductivity and structural deterioration during battery cycling have hindered the widespread application of Na₃V₂(PO₄)₃ (NVP). In response to these challenges, we advocate for a technique involving the application of carbon modifications to NVP to enhance its suitability as cathode material. This work involves the synthesis of N/Cl co-modified in situ carbon coatings derived from clozapine (CZP) through a facile hydrothermal route. By incorporating N elements into the carbon layer, we promote the generation of defects, which increases the exposure of active sites and facilitates greater involvement of Na⁺ in the electrochemical reaction. Additionally, the integration of chloride ions into the carbon layer enhances the electronic conductivity of NVP. Ex-situ X-ray diffraction (XRD) analysis reveals that the modified carbon layer acts as a buffer against the Na⁺-induced volume expansion of the single cell during the de-embedding process. Furthermore, ex-situ X-ray photoelectron spectroscopy (XPS) results show a reversible transformation between pyrrolidone N, pyridine N, and graphite N, resulting in improved electron transfer rate and maintenance of the carbon skeleton's stability, thereby providing robust support for NVP. Accordingly, the CZP-5 % displays a remarkable reversible capacity of 115.6 mAh g^-1 at 0.1C, suggesting full activation of Na⁺. It can deliver 85 and 84.6 mAh g^-1 at 20 and 40C, even after 1500 cycles, the residual capacity remain at 72.7 and 67.6 mAh g^-1, respectively, with high retention values of 85.5 % and 79.9 %. The optimized CZP-5 % sample is subjected to thermal stability testing using an adiabatic accelerating calorimeter, systematically evaluating the battery's thermal stability and providing valuable insights for the design of the battery management system.