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

Na 3 V 2 (PO 4 ) 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 V 4+ /V 5+ redox reaction is crucial for the practical application of NVP cathodes. In this study, a high-entropy NVP cathode with carbon coating (Na 3 V 1.5 (CrMnFeMgAl) 0.5 (PO 4 ) 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 V 3+ /V 4+ /V 5+ 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. This study presents a high-entropy NASICON-type cathode, Na 3 V 1.5 (CrMnFeMgAl) 0.5 (PO 4 ) 3 @C, which enhances electronic and ionic conductivity as well as structural stability for sodium-ion batteries.