High-entropy doping for high-performance Na₃V₂(PO₄)₃@C cathode materials in sodium-ion and hybrid lithium/sodium-ion...

The rising demand for cost-effective and safe energy storage systems has ignited strong global interest in advanced cathodes that surpass lithium-ion batteries in practical applications. Herein, we propose a composite material in which five ions, Ti⁴⁺, Mn²⁺, Fe²⁺, Zr⁴⁺, and Mo⁶⁺, are doped into the lattice of Na₃V₂(PO₄)₃ and a uniform carbon-coating layer is applied to its surface, resulting in the formation of high-entropy doped Na₃V₂(PO₄)₃@C materials (HENVP@C). When employed as the cathode material for Sodium-ion batteries (SIBs) and hybrid lithium/sodium-ion batteries (HLSIBs), HENVP@C shows remarkable Li⁺/Na⁺ storage capabilities. The results of electrochemical performance tests on half-cells reveal that HENVP@C exhibits a high capacity, along with excellent cycle life and stability. High-entropy doping effectively stabilizes the NASICON structure of HENVP@C, enhances ionic conductivity, and optimizes ion diffusion kinetics, particularly improving its dual-ion pseudocapacitive storage capability. In addition, the surface carbon coating improves the electronic conductivity of the material. The insights presented in this work provide new ideas for designing cathode materials for SIBs and HLSIBs.