Cu9S5/Fe2O3 Nanospheres as Advanced Negative Electrode Materials for High Performance Battery-like Hybrid Capacitors

In our work, a Cu9S5/Fe2O3 composite with nanosphere morphology is prepared by an efficient one-pot solvothermal selective sulfurization. The structure investigation confirms that there is uneven charge distribution at the interfaces of Cu9S5 and Fe2O3. Furthermore, the corresponding electrochemical measurements reveal the detailed redox kinetics process about Cu2+/Cu+, Fe3+/Fe2+, and (S2)−/S2–. When the obtained Cu9S5/Fe2O3 composite is used as a negative electrode, it exhibits a high specific capacity (348.2 mA h g–1 at 1 A g–1) with good rate capability. Moreover, a hybrid capacitor (HCP) assembled with Cu9S5/Fe2O3 as negative and Ni–Co hydroxide/Cu(OH)2/CF as positive electrodes, respectively, shows a high energy density with a corresponding high power density (64.54 W h kg–1 at 757.81 W kg–1) and a high specific capacitance (47 mA h g–1 at 1 A g–1) with a capacity retention of 45.68% (21.5 mA h g–1) even at 20 A g–1 in a solid-state gel electrolyte. Thus, a facial fabricated anode material with outstanding electrochemical properties for HCPs is provided.