Hierarchically Structured rGO/MoS2 Flexible Films via Facile Synthesis for High Performance K-Ion Supercapacitors

This study presents a hierarchically structured, free-standing rGO/MoS2 hybrid film fabricated through a facile vacuum filtration and thermal reduction approach, offering a cost-effective strategy for high-performance K-ion supercapacitors. The optimized composite architecture features nanoporous, layer-stacked channels and expanded interlayer spacing, enabling efficient ion diffusion and abundant electroactive sites. The rGO/MoS2 electrode demonstrates exceptional capacitive performance, delivering a gravimetric capacitance of 378 F g-1 and a record volumetric capacitance of 787 F cm-3 at 1 A g-1, attributed to the synergy between the conductive rGO network and the pseudocapacitive properties of MoS2. The symmetric supercapacitor cell assembled with rGO/MoS2 electrodes and an aqueous electrolyte (3 mol L-1 KOH) demonstrated a high energy density of 7.6 mWh cm-3 with power density of 0.36 W cm-3, whereas supercapacitor with organic electrolyte (1 mol L-1 MeEt3NBF4) displayed 26 mWh cm-3 at 1.4 W cm-3. Both supercapacitors showed excellent cycling lifespan with capacitance retention of 100% after 480,000 and 270,000 cycles, respectively. These findings suggest the excellent electronic conductivity of rGO and the electrochemically active MoS2 synergistically contribute to the outstanding supercapacitor performances.