Structural engineering of bimetallic copper molybdate with high energy storage performance for long‐life hybrid supercapacitors

Abstract Morphologically controlled synthesis of metal oxide‐based materials has attracted significant attention to enable the capacity and redox performance of faradaic‐type hybrid supercapacitors (H‐SCs). In this work, we designed hollow‐structured copper molybdate (Cu 3 Mo 2 O 9 ) with hollow flowers (CM HFs) and hollow spheres (HSs) were facilely prepared by solvent‐mediated hydrothermal method. The aqueous environment in the hydrothermal system facilitates anisotropic crystal growth and self‐assembly of nanoplates into three‐dimensional CM HFs architecture, which showed high surface area and enhanced electrolyte accessibility. The electrochemical performance revealed that the CM HFs showed better redox behavior with longer charge–discharge times, and lower resistance compared to CM HSs. As a result, the CM HFs showed a higher specific capacitance of 530 F g −1 at 2 A g −1 and faster ion diffusion with a capacitance retention of 94.1% after 10,000 cycles. Moreover, a two‐electrode H‐SC was fabricated using CM HFs as the positive electrode and activated carbon as the negative electrode, which achieved a high energy density of 33.24 Wh kg −1 and a power density of 5250 W kg −1 along with excellent cycling stability. Aiding from the high energy storage performance of H‐SC, the devices in series successfully powered LEDs, demonstrating their potential for flexible and durable energy storage applications.