Preparation and Electrochemical Properties of Rare-Earth Ion(RE=La3+,Gd3+,Lu3+)Doping Na3V2(PO4)3/C Cathode Materials
Na3V2(PO4)3(NVP)has attracted much attention due to its high capacity and high voltage platform.However,its further development is severely limited by its poor intrinsic electron and ionic conductivity.Here-in,the conductivity of NVP is improved by doping rare earth ions(La3+,Gd3+,Lu3+)using a solid-state reaction method assisted by ball walling.The successful rare earth ions(La3+,Gd3+,Lu3+)doping in NVP/C structure was confirmed by X-ray diffraction(XRD),scanning electron microscopy(SEM)and X-ray energy spectrum(EDS).The influence of rare earth ions(La3+,Gd3+,Lu3+)doping on the electrochemical performance of NVP/C was studied by electrochemical tests.The results show that La3+and Gd3+doping can effectively improve the elec-trochemical performance of NVP/C.NVP/C-La0.03 and NVP/C-Gd0.03 present an initial discharge capacity of 110 and 105.5 mAh·g-1 at 1C with the capacity retention rates of 97.5％and 95.7％after 200 cycles.Among the Na3V2-xREx(PO4)3/C samples,NVP/C-La0.03 has the best electrochemical performance,a high discharge capaci-ty of 100.05 mAh·g-1 at 5C after 500 cycles.Therefore,proper rare earth ions doping can improve the electro-chemical performance of NVP/C materials to a certain extent,which provides basic research support for further exploration of cathode materials for sodium-ion batteries.
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