Solvothermal growth of silver-doped vanadium pentoxide microurchins as a cathode material for all-solid-state asymmetric supercapacitors

This study aims to improve the electrochemical properties of vanadium pentoxide by inserting silver cations into the vanadium oxide lattice. The porous silver-doped V2O5 (Ag-V2O5) microurchins were grown via a facile one-step solvothermal process. The enhanced mesoporosity and interlayer d-spacing upon silver-doping, as confirmed by Brunauer-Emmett-Teller (BET) and X-ray diffraction analyses, played an important role in facilitating the intercalation/de-intercalation of electrolyte ions and thus enhancing the capacitive performance of V2O5. The Ag-V2O5 electrode delivered a superior capacitance of 535.6 F/g at 0.5 A/g and a higher rate capacity of 78.8% in non-aqueous lithium perchlorate electrolyte compared to sodium perchlorate electrolyte. Furthermore, the specific capacitance of V2O5 was remarkably increased by similar to 56% upon 5.33 at% Ag-doping. An all-solid-state asymmetric supercapacitor (ASC) was fabricated using Ag-V2O5 as the cathode, activated carbon cloth as the anode, and LiClO4-loaded poly(acrylonitrile-co-1-vinylimidazole-co-itaconic acid) as a solid electrolyte. The ASC was stably operating in a wide potential window of 0-1.6 V and delivered a high energy of 53.8 Wh kg(-1). Most importantly, the ASC exhibits a slow self-discharge rate with only 7.7% voltage loss after 17 h when charged at 1.6 V. Hence, these impressive electrochemical performances of Ag-V2O5 make it a promising cathode material for next-generation supercapacitors.