Robust, Flexible, and Binder Free Highly Crystalline V2O5 Thin Film Electrodes and Their Superior Supercapacitor Performances

Modern wearable technologies require highly efficient energy storage devices for improving their performance attributing a controlled shape and flexibility. Here, the present study is focused on the fabrication of a highly improved V2O5 thin film based supercapacitor. Symmetric device of V2O5 parallel to PVA-KOH parallel to V2O5 was fabricated using thin flexible electrodes prepared by a thermal evaporation technique. The symmetric supercapacitor devices were fabricated using both annealed and as-prepared films separately, and their performance characteristics were compared. The V2O5 symmetric device having pseudocapacitive behavior delivered a maximum specific areal capacitance of 9.7 mF cm(-2) at a scan rate of 10 mV s(-1). The symmetric microcapacitor also showed promising performance even after being bent at 60 and 120 degrees. This indicates the reliability of the fabricated devices for flexible electronic applications. Moreover, the symmetric capacitor showed excellent capacitance retention (95%) even after 30 000 cycles with the coulombic efficiency of 99%. Furthermore, practical feasibility of the as fabricated devices was demonstrated by lighting blue light-emitting diodes by connecting them in series. On the other hand, characteristics of the V2O5 thin films were also studied using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and atomic force microscopy analysis.