Achieving highly reversible and fast sodium storage of Na4VMn(PO4)3/C-rGO composite with low-fraction rGO via spray-drying technique

Highlights: • A Na₄VMn(PO₄)₃/C-rGO cathode material for sodium-ion battery was prepared by simple and scalable spray-drying technique. • Low-fraction rGO nanosheets in the Na₄VMn(PO₄)₃/C-rGO hybrid achieved high electronic conductivity. • The Na₄VMn(PO₄)₃/C-rGO with merely 2.14 wt% rGO revealed ultrahigh rate capacity of 102.6 mA h g⁻¹ at 50 C and excellent cycling stability. • Analyses of the in-situ XRD, GITT and pseudo-capacitance were conducted to elucidate the mechanism for the excellent performance in sodium storage. NASICON-type (Na super ionic conductor) Na₄VMn(PO₄)₃ (NVMP) cathode material has attracted increasing attention due to its higher sodium de-/intercalation voltage, lower cost and greener resources compared with Na₃V₂(PO₄)₃. However, the poor electronic conductivity limits the exploitation of its electrochemical performance. In this work, we achieved an ultrahigh rate capable and long cycle life NVMP/C-rGO composite using the simple and scalable spray-drying technique, in which low-fraction rGO nanosheets (2.14 wt%) highly dispersed and bridged the carbon shelled NVMP nanoparticles to form an effective electron conductive network. Benefiting from this favorable nano-architecture, the elaborately designed NVMP/C-rGO composite exhibited excellent performance as cathode in sodium ion batteries, delivering reversible capacities of 105.5 mA h g⁻¹ at 1 C (1 C = 110 mA h g⁻¹) and 102.6 mA h g⁻¹ at 50 C with capacity retention of 90.6% (1 C) and 80.4% (50 C) over 500 cycles, respectively. This is the highest rate performance for Na₄VMn(PO₄)₃ materials reported so far. This work provides a practicable tactic for fabricating advanced polyanion-type cathode materials which can be commercially scale up for sodium energy storage.