MOF-Templated sword-like Co3O4@NiCo2O4 sheet arrays on carbon cloth as highly efficient Li-O2 battery cathode

Highly effective cathode materials are critical to improve existing Li-O-2 batteries. In this paper, we report a freestanding Co3O4@NiCo2O4 sheet array cathode, which is prepared by in-situ growing an array of sword-like cobalt-based metal-organic framework (Co-MOF) sheets on a carbon cloth (CC) substrate, followed by impregnated with nickel nitrate solution and pyrolyzed in air flow. The Co3O4@NiCo2O4/CC cathode exhibits excellent ORR/OER bifunctional activity and high cathodic performance in a Li-O-2 battery, achieving a specific capacity of 10645 mAh g(-1) and a stability of 225 cycles. We suggest the high performance of our cathode can be ascribed to its well-defined 3D sheet array structure, which can facilitate O-2 diffusion and electrolyte impregnation, provide sufficient space for the discharge products, and the synergistic effect between Co3O4 and NiCo2O4. This work provides an effective method for the rational design of electrode composition and structure.