Multi-type cubic ComXn (X = O, S, Se) induced by zeolitic imidazolate framework (ZIF) as cathode materials for aluminum battery

Since the energy storage mechanism of metal oxides, sulfides and selenides as cathode materials for aluminum ion batteries (AIBs) is still unclear, we successfully prepared multi-type cubic ComXn (X = O, S, Se) by ZIF induction to study and analyze the energy storage mechanism. Through ex-situ XRD and XPS characterization, it is found that Co3O4 and Co3S4 only cause the valence change of Co element for energy storage due to the insertion and extraction of Al3+, while in CoSe2, not only Co but also Se element is involved in the redox reaction. Besides, CoSe2 exhibits higher operating voltage and excellent discharge capacity compared to Co3O4 and Co3S4. At 100 mA g−1, CoSe2 exhibits two operating voltages at 0.8 V and 1.8 V, and its first discharge capacity is 785.6 mAh g−1, while the discharge voltage of Co3O4 and Co3S4 is only about 0.6 V, and the discharge capacities are 388.3 mAh g−1 and 579.7 mAh g−1, respectively. After 500 cycles, the discharge capacities of CoSe2 are maintained at 148.9 mAh g−1 at 500 mA g−1. In addition, DFT proves that, compared with Co3O4 and Co3S4, CoSe2 is more conducive to the surface adsorption and diffusion of AlCl4−, which lays a key foundation for the research on the cathode materials of aluminum batteries.