Microwave-Assisted Rational Designed CNT-Mn3O4/CoWO4 Hybrid Nanocomposites for High Performance Battery-Supercapacitor Hybrid Device

Extensive research interest in hybrid battery-supercapacitor (BSH) devices have led to the development of cathode materials with excellent comprehensive electrochemical properties. In this work, carbon nanotube (CNT)-Mn3O4/CoWO4 triple-segment hybrid electrode is synthesized by using a two-step microwave-assisted hydrothermal route. Systematic physical characterization revealed that, with the assistance of microwave, granular Mn3O4 and spheroid-like CoWO4 with preferred orientation, and oxygen vacancies are stacked or arranged on CNTs skeletons to construct a rational designed hybrid nanocomposite with abundant heterointerfaces and interfacial chemical bonds. Electrochemical evaluations show that the synergistic cooperation in CNT-Mn3O4/CoWO4 resulted in an ultra-high specific capacity (1907.5 C g(-1)/529.8 mA h g(-1) at 1 A g(-1)), a wide operating voltage window (1.15 V), the satisfactory rate capability (capacity maintained at 1016.5 C g(-1)/282.3 mA h g(-1) at 15 A g(-1)), and excellent cycling stability (117.2% initial capacity retention after 13000 cycles at 15 A g(-1)). In addition, the assembled CNT-Mn3O4/CoWO4//N doped porous carbon (N-C) BSH device delivered a stable working voltage of 2.05 V and superior energy density of 67.5 Wh kg(-1) at power density of 1025 W kg(-1), as well as excellent stability (92.2% capacity retained at 5 A g(-1) for 12600 cycles). This work provides a new and feasible tactic to develop high-performance transition metal oxide-based cathodes for advanced BSH devices.