The utilization of polyanion Na3V2(PO4)3 as a cathode material in NASICON-type sodium ion batteries is hindered by the high cost of raw materials and limited energy density. To address this issue, a double doping strategy using Mn2+ and Al3+ was adopted in Na3V2(PO4)3 based on the charge balance theory, aiming to enhance the electrochemical performance. The Na3.5V1.4Mn0.5Al0.1(PO4)3/C composite was synthesized, exhibiting a reversible capacity of 118 mAh g-1 at 0.2 C and a decent capacity retention of 81.4% after 200 cycles. Furthermore, the midpoint voltage analysis revealed that, after 200 cycles, the voltage plateau of NMVP dropped drastically from 3.42 V to 3.28 V, while the voltage plateau value of NMVPS- 0.05 only experienced a slight decrease from 3.42 V to 3.39 V, indicating the positive impact of Al doping on the electrochemical performance. These results suggest that the Na3.5V1.4Mn0.5Al0.1(PO4)3/C composite has great potential as a cathode material for sodium ion batteries.
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