Synergetic effects from a high-entropy NASICON-type cathode for advanced sodium-ion batteries

Abstract

Na₃V₂(PO₄)₃ (NVP) is recognized as one of the most promising NASICON-type cathodes for sodium-ion storage. Enhancing electronic conductivity and further ensuring long-term structural stability when activating the high-voltage V⁴⁺/V⁵⁺ redox reaction is crucial for the practical application of NVP cathodes. In this study, a high-entropy NVP cathode with carbon coating (Na₃V_1.5(CrMnFeMgAl)_0.5(PO₄)₃@C, HE-NVMP@C) has been designed and synthesized. Due to the enhanced electronic/ionic conductivity facilitated by the carbon coating and lattice distortion from the high-entropy effect, HE-NVMP@C exhibits improved high-rate performance. Additionally, benefiting from the collaboration between the doped heteroatoms, HE-NVMP@C can effectively activate V³⁺/V⁴⁺/V⁵⁺ redox reactions within the 2.5–4.3 V voltage window while maintaining excellent structural stability over extended cycles. This work provides an efficient approach to enhance the electrochemical performances of NASICON-type cathodes for sodium-ion batteries.