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

Abstract

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||PVA-KOH||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°. 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.