Chemically Synthesized Cu3Se2 Film Based Flexible Solid-State Symmetric Supercapacitor: Effect of Reaction Bath Temperature

Recently, as the importance of energy storage increases, the development of high-performance supercapacitor electrode materials has stimulated a great deal of scientific research. The electrochemical performance of the electrode strongly depends on material structure. In this work, copper selenide (Cu3Se2) electrodes are prepared using the chemical bath deposition method in different temperature ranges (323–353 K). The tetragonal crystal structure of the electrodes exhibits the specific surface area of 5.32 m2 g–1. This electrode demonstrates excellent specific capacitance of 1285 F g–1 at an applied current density of 0.5 A g–1 and cycling stability of 92% after 3000 galvanostatic charge–discharge (GCD) cycles at 2.5 A g–1. The solid-state symmetric supercapacitor, Cu3Se2/PVA–KOH/Cu3Se2, fabricated using this electrode exhibits a specific capacitance of 132 F g–1 at a scan rate of 5 mV s–1 and stability of 91% after 5000 cyclic voltammetry (CV) cycles at a scan rate of 100 mV s–1. The flexibility study shows a fabricated supercapacitor device retains 95% specific capacitance at a bending of 165°. This study sheds a light on the possible use of copper selenide in energy storage applications, especially in supercapacitors.