Controllable synthesis of flower-like MnV₂O₆·2H₂O microsphere as electrode for advanced hybrid supercapacitors

Exploring novel electrode materials with rational morphology and structure is critical for the development of supercapacitors. In this paper, flower-like MnV₂O₆·2H₂O microspheres have been controllably synthesized through a methanol and ethylene glycol assisted solvothermal method. Especially, the methanol solvent (structure-directing agent) induces the assembly process of the recrystallized nanosheets into flower-like microspheres, and the assistance of ethylene glycol (chelating agent) can effectively reduce the microsphere size through the strong complexation between metal ions and ethylene glycol. Benefiting from the unique three-dimensional (3D) hierarchical porous structure, the flower-like MnV₂O₆·2H₂O microsphere electrode has an outstanding charge capacity (374.1 C·g⁻¹ at 1 A·g⁻¹), good rate capability, and excellent electrochemical stability (92.7 % capacity retention after 10,000 cycles). After being assembled into supercapacitor, the fabricated MnV₂O₆·2H₂O//AC device exhibits a superior energy density of 35.7 Wh·kg⁻¹ at the power density of 571.7 W·kg⁻¹. These excellent properties demonstrate its potential application prospect in supercapacitor.