Effective construction of binder-free Ni-Co hydroxides Co9S8/Ni3S2 cubic-honeycomb-like granules for boosted alkaline zinc batteries

Here, 3D (three dimensional) porous Co9S8/Ni3S2 (CNS) nano-cubes with Ni-Co hydroxides nanoflakes cladding (CNS-NCOOH) was engineered through a convenient and easy-to-scale hydrothermal combined with chemical bath deposition strategy. The enriched voids between Ni-Co bimetallic hydroxide nanoflakes and exclusive micron-level 3D pores of nickel substrate were interconnected and collaboratively supply convenient ion diffusion pathways, as well as adequate free space to accommodate their volume variation during circulation. Meanwhile, the tailored core-shell architecture can stimulate the structural ruggedness of the CNS-NCOOH in alkaline electrolytes during cycling. Consequently, the CNS-NCOOH composites equipped with nickel-cobalt hydroxide nanoflakes exhibited superior performance in a three-electrode system compared to individual CNS-based cubes electrodes, which was primarily credited to the pore-rich, structurally stable, highly-exposed active sites on the surface, as well as the intimate contact between Ni-Co sulfides and Ni-Co hydroxides. In the case of alkaline zinc batteries, the assembled CNS-NCOOH//Zn cells displayed a discharge capacity of 384 mu Ah cm-2 at 4 mA cm-2 and a capacity retention of 105.8% after 4000 cycles at 12 mA cm-2, indicating a significantly improved electrochemical performance over CNS//Zn cells. These findings provided insights into the exploitation of innovative electrode materials for a high-performance alkaline zinc battery.