Effect of High-Entropy Micro-Doping on the Structure and Sodium Storage Performance of Na₃V₂(PO₄)₃ AITranslate

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Chinese Library Classification Number:TM912.9[电气工程—电力电子与电力传动]

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The low intrinsic electronic conductivity of Na₃V₂(PO₄)₃(NVP)leads to poor rate performance and significant capacity decay during electrochemical reactions.Therefore,in this study a high-entropy doping strategy is adopted by introducing five trace metal ions into the V-site of NVP to design a high-performance sodium-ion battery cathode material,Na₃V_1.9(MnCrCaMgAl)_0.02(PO₄)₃/C(HE-NVP/C)composite,which was synthesized using an improved sol-gel combustion method.The structure of the material was characterized by X-ray diffractometer,specific surface area and porosity analyzer,scanning electron microscope and transmission electron microscope,and its electrochemical performance was evaluated by battery test system and electrochemical workstation.The results show that the synthesized HE-NVP/C composite is composed of micron-sized blocky particles with mesoporous structure and uniform coating of amorphous carbon layer.High-entropy micro-doping preserves the rhombohedral lattice structure of NVP,and the unit cell volume is almost unchanged due to the synergistic effect of five doping elements.High-entropy micro-doping can significantly increase the porous structure of the NVP/C electrode material,thereby shortening the transport path of sodium ions,increasing the specific surface area of the electrode material,and providing more electrochemical active sites,which collectively improve the sodium storage performance.The electrochemical reversibility,electronic conductivity and sodium-ion diffusion rate of HE-NVP/C sample are higher than those of NVP/C.Consequently,HE-NVP/C exhibits excellent rate capability and cycling performance.As the rate increases from 0.2 C to 10 C,the average discharge specific capacity of the HE-NVP/C sample decreases from 113.08 mA·h/g to 103.60 mA·h/g.When the rate is returned to 0.2 C,the capacity recovers 112.02 mA·h/g.At a rate of 1 C,the initial discharge specific capacity of the HE-NVP/C sample is 108.16 mA·h/g and the capacity retention rate is 93.39%after 100 cycles.At a rate of 10 C,the HE-NVP/C sample exhibits an initial discharge specific capacity of 102.16 mA·h/g and maintains a capacity retention of 70.58% after 500 cycles.