Porous ZnO Nanosphere Inherently Encapsulated in Carbon Framework as a High-Performance Anode For Ni-Zn Secondary Batteries

Nickel-zinc (Ni-Zn) secondary battery that is environmentally friendly and inexpensive has been regarded as a promising rechargeable battery system. However, the generation of deformation and dendrites of the traditional zinc anode during the cycling can cause capacity degradation and impede its practical application. Herein, we design a hierarchical ZnO nanosphere coated with an inherently derived ZIF-8 porous carbon shell (ZnO@C_ZIF-8) using a simple controllable method. The conductive carbon shell and porous ZnO core can provide more active sites, allow the fast transfer of electrons, and buffer the volume expansion of the electrode effectively. Benefiting from the synergistic effect amid the inherently ZIF-8-derived carbon shell and ZnO core, ZnO@C_ZIF-8 nanospheres exhibit a satisfying capacity of 316 mAh g^-1 at a current density of 1 A g^-1 after 50 cycles and an outstanding rate capacity when acting as the anode for a Ni-Zn secondary battery with merchant agglomerative Ni(OH)₂ as the cathode. These results imply that the ZnO@C_ZIF-8 nanosphere is a hopeful anode for a high-energy Ni-Zn secondary battery.