Hierarchical construction of amorphous NiCo-OHS@ZnS hollow spheres with optimized reaction kinetics via ion exchange-etching strategy for energy storage

Nickel-based hydroxides are among the most attractive cathode materials developed to date for the energy storage in hybrid supercapacitor, though their reactive activity and structural stability are still unsatisfactory. Herein, a continuous ion exchange-etching strategy is proposed to construct the NiCo-OHS@ZnS electrode materials based on nickel cobalt hydroxide (NiCo-OH) hierarchical hollow spheres. According to the experimental results, the fabricated hierarchical hollow structures with amorphous nanosheets and hetero phases are conducive to improving the electrochemical active area, ions/charges transfer capability, intrinsic properties and adsorption energies for redox reactions. Thanks to its unique electronic structure and three-dimensional open framework, the optimized [email protected] electrode presents the excellent electrochemical performances with an impressive capacity of 1655 C g−1 at 1 A g−1 and rate capability of 81.9 % (30 A g−1). Simultaneously, it is found that there is an obvious phase evolution from the as-prepared material to its corresponding hydroxide, accompanied with the formation and adsorption of SO42−/Zn2+ ions during charge/discharge process. Moreover, the assembled hybrid supercapacitor yields an outstanding energy density of 61.1 Wh kg−1 at a power density of 806.0 W kg−1. This work provides a reliable guidance for modulating the structures and properties of electrodes in energy storage.