MoO₂/a-CNT/rGO as electrode material for all-in-one flexible supercapacitor with integrated structure and function

Flexible hydrogel based supercapacitors are ideal wearable energy storage devices due to their excellent power density, high charge/discharge efficiency. However, conventional laminated and sandwich structures could increase the interfacial contact resistance between the electrolyte and electrodes. Herein, a new all-in-one flexible supercapacitor with integrated structure and function was developed to avoid displacement and delamination during deformation and reduce the interface contact resistance. The all-in-one flexible supercapacitor is prepared from in situ synthesis and polymerization of MoO₂/acidified carbon nanotubes (a-CNTs)/reduced graphene oxide (rGO) electrode materials into the PVA hydrogel. The unique freeze-thaw cycle method significantly enhances the integrity of the capacitor, making it exhibit enhanced specific capacitance (61.1 mF·cm⁻² at a current density of 0.2 mA·cm⁻²), excellent cycling stability (99.4 % capacity retention over 4000 cycles) and flexibility (243.3 % of tensile rate). Experimental and computational analyses probe into the root of the improvement of the electrochemical performance, confirming the significance of the 3D conductive network structure. This strategy furnishes a new reliable approach and paves the way for further study of flexible energy storage devices.