Construction of an Ultra-High-Energy Density Hybrid Supercapacitor with Self-Assembled 3D Hydrangea Flower-like Mo-rich CoMoO4 Microstructures

The accumulation of two-dimensional nanoflake-like units into three-dimensional (3D) hierarchical mesoporous flower-like microstructures can introduce abundant electroactive surface sites and large contact areas with the electrolyte and enable fast ion/electron transport during the electrochemical process. We propose a simple method of constructing a 3D hydrangea flower-like mesoporous Mo-rich CoMoO4 (CMO) electrode via the solvothermal route (CMO-ETH) with excellent electrochemical characteristics. This morphology arises from the self-assembly of primary nanoparticles into flake-like units, then transformed into hydrangea flower-like microstructures. Compared with the CMO-DIW battery-type electrode (hydrothermally synthesized electrode), the CMO-ETH had a higher specific capacity of 678 C g(-1) at a current density of 1 A g(-1). The fabricated CMO-ETH//activated carbon hybrid supercapacitor (HSC) exhibited an ultra-high energy density of 103.4 Wh kg(-1) at a power density of 750.5 W kg(-1). We also successfully turned on the red and green LEDs for 3 minutes after connecting two HSCs in series.