Amorphous Ni-Co-S nanocages assembled with nanosheet arrays as cathode for high-performance zinc ion battery

The selection and development of cathode of alkaline zinc batteries (AZBs) is still hindered and often leads to poor rate capability and short cycle life. Here, amorphous hollow nickel-cobalt-based sulfides nanocages with nanosheet arrays (AM-NCS) are designed and constructed with ZIF-67 as the self-template to exchange with Ni2+ and S2− by using a two-step ion exchange method. The synthesized AM-NCS possess the high specific capacity (160 mAh/g at 2 A/g), and the assembled battery has excellent rate performance (146 mAh/g reversible capacity at 5 A/g). The assembled device has excellent rate performance (155 mAh/g at 2 A/g) and long cycling stability (7000 cycles, 62.5% of initial capacity). The excellent electrochemical properties of the electrode materials are mainly attributed to the unique structure, in particular, polyhedron structure with hollow structure can improve the cyclic stability, and the amorphous structure can expose more reactive sites on the surfaces of nickel, cobalt and sulfur. This work provides a new strategy for the design and fabrication of high performance cathode materials for AZBs. [Display omitted] The AM-NiCoS of an amorphous hollow structure was synthesized by using ZIF-67 as a self-template for a cation exchange reaction with Ni2+, followed by an anion exchange reaction with S2−.We assembled zinc ion batteries using synthetic AM-NiCoS as a positive material, showing excellent electrochemical properties and mechanical stability.