All-Solid-State Supercapacitor Based on Advanced 2D Vanadium Disulfide/Black Phosphorus Hybrids for Wearable Electronics

Vanadium disulfide–black phosphorus (VS2–BP) hybrids were synthesized by a one-pot hydrothermal-assisted method to achieve enhanced electrochemical activity for supercapacitor applications. The concentration of BP was optimized to prevent the restacking nature of VS2 and to enrich the active edges for electrolytic ion intercalation. The charge storage kinetics of the best-performing VS2–BP as an active electrode has demonstrated the dominance of the pseudocapacitive nature of the material. Furthermore, by sandwiching with a PVA/K2SO4 gel electrolyte, an all-solid-state (ASS) vanadium disulfide–black phosphorus-50 mg (VS2–BP-50) symmetric device was developed on highly conductive carbon paper. The ASS VS2–BP-50 symmetric device displays the highest specific areal capacitance of 203.25 mF/cm2 and exhibits the maximum areal energy density of 28.22 μW h cm–2 at an areal power density of 596.09 mW cm–2, outperforming the previous literature. To understand the origin of the high quantum capacitance, we used density functional theory (DFT) and found that the charge accumulation region between VS2 and BP monolayers and the charge transfer are the origin of the improved density of states in the VS2–BP hybrid. Moreover, exceptional mobility of K+ ions and a higher diffusion rate were observed using the DFT method.