Photo-assisted capacitive performance of V2O5 supercapacitor

Abstract

A photo-assisted energy storage system enables a new pathway to utilize unlimited solar energy. Herein, V2O5 was synthesized using a simple, time-saving thermal decomposition process. The V2O5 samples were characterized thoroughly. The photo-electrochemical performances of the as-prepared V2O5 samples were evaluated using a three-electrode system. The material showed increased specific capacity from 45 C g−1 to 69 C g−1 in the presence of light. The photo-assisted V2O5||V2O5 and V2O5||AC (activated carbon) ASC (asymetric supercapacitors) FTO devices effectively responded to the light sources. The areal capacity of the V2O5||AC ASC FTO photo-assisted charging device was 112 mC cm−2 under the given light intensity, whereas the device tested using the conventional process (without light irradiation) delivered only 45 mC cm−2 at the same current density. Further, the asymmetric FTO device delivered high specific energy and power density of 9.8 Wh kg−1, and 29 W kg−1 respectively, in the presence of light. Notably, the symmetric FTO device was photo charged to 200 mV in 1 h without any external current and was discharged in the dark at 0.01 mA cm−2. On the other hand, V2O5 symmetric coin cell delivered excellent cycle stability over 40,000 cycles at different current rates with an outstanding coulombic efficiency of 98%. These results are a clear indication that the photo charging-based supercapacitor will pave an innovative path in constructing futuristic energy storage devices.