Freestanding, Three-Dimensional, and Conductive MoS2 Hydrogel via the Mediation of Surface Charges for High-Rate Supercapacitor

Conductive hydrogels with fluidic nanochannels represent one of the most promising capacitive electrodes due to their highly porous structure for the rapid kinetics of electrolyte ion transport. Recent advances in conducting polymers, graphene, and transition metal carbide (MXene)-based hydrogel materials have indicated appealing potential in electrochemical energy storage. The construction of conductive transition-metal dichalcogenide (TMD) hydrogels is still a challenge. In this work, by understanding the colloidal properties of solution-processable 1T molybdenum disulfide (MoS 2 ) nanosheets, we develop a surface-charge-control strategy by changing the electrostatic repulsions for fabricating a freestanding conductive MoS 2 hydrogel with three-dimensional (3D) porous structure. Given the interpenetrating ionic transport network, the conductive MoS 2 hydrogel, as the electrode of symmetric supercapacitors, exhibits an extremely small time constant of 0.09 s and high power density of 7.0 × 10 4 W kg –1 under a large current density of 50 A g –1, which is superior to the conventional 2D-MoS 2 electrode.