Ultrafine chromium oxide (Cr2O3) nanoparticles as a pseudocapacitive electrode material for supercapacitors

In contemporary electrochemical supercapacitors, the capacitive nature of the energy storage mechanism seems to become an approaching alternative to lithium ion batteries in near future. In this context, herein, we have investigated Cr2O3 ultrafine particles with excellent structural and electrochemical features as a promising capacitive energy candidate for supercapacitors. We have reported both, the EDL and pseudocapacitive features of ultrafine Cr2O3 nanoparticles during charging-discharging process in aqueous solution (6 M KOH) and also separated these features by using the mathematical equation for total current “i(V) = k1v1/2+ k2v” in the Voltammogram. Along with the unique electrochemical characteristics, the aforementioned analysis for Cr2O3 nanoparticles is done for the first time. Furthermore, a superior specific capacitance of 340 F g−1 at a specific current density of 0.5 Ag-1 along with an excellent cycling retention of 85% after 3000 cycles is obtained. On coupling with an activated carbon electrode, the asymmetric supercapacitor demonstrated the remarkable specific energy and the power density of 12.5 Wh kg−1 and 312.5 W kg−1 respectively.