Evolution of α-V2O5 into electrochemically transformed NaV3O8 structure: Structural changes and supercapacitor application.

[Display omitted] • Green synthesis of α-V 2 O 5 nanosheets using Aloe Vera leaf extract. • Electrochemical phase transformation of α-V 2 O 5 to NaV 3 O 8 nanosheets. • Structural and morphological evolutions during electrochemical phase transformation. • Specific capacitance of 640.10 F g−1 at 0.5 A g−1 NaV 3 O 8 nanosheets electrode. Nowadays, cost-effective and environmentally friendly supercapacitors (SCs) with high energy and power densities are gaining significant research attention since they could broaden the application of capacitors. The present study demonstrates a low-cost green synthesis technique to prepare the α-V 2 O 5 phase using Aloe Vera leaf extract. X-ray diffraction technique confirmed the formation of the orthorhombic α-V 2 O 5 phase. The prepared α-V 2 O 5 was employed as an electrode material for SC application. During an electrochemical cyclic voltammetry test in Na 2 SO 4 electrolyte, Na+ ions intercalation and de-intercalation processes resulted in a phase transformation of α-V 2 O 5 to NaV 3 O 8. Structural transformation (i.e., orthorhombic to monoclinic crystal structure) and morphological changes were also observed during the electrochemical phase conversion process. This electrochemical phase transformation process improved the overall supercapacitive performance of the α-V 2 O 5 material. Such electrochemically converted NaV 3 O 8 displayed a maximum specific capacitance of 640.1 F g−1 at 0.5 A g−1 with a long cyclic stability. Furthermore, the AC // NaV 3 O 8 asymmetric SC coin cell device delivered a maximum energy density of 62.6 Wh kg−1 and a power density of 7.3 kW kg−1 along with an excellent cycling stability of ∼81 % over 5000 GCD cycles. [ABSTRACT FROM AUTHOR]