Design of Three-Dimensional Air Cathode in Zinc-Air Batteries

Three-dimensional (3D) air cathodes play a pivotal role in enhancing oxygen electrocatalysis. 3D materials have arisen as a tremendous research hotspot for designing the highly promising and cost-effective air electrodes for zinc–air batteries. 3D materials significantly contribute to the energy density, power density, and capacity of battery and eventually the stability. 3D materials for zinc–air batteries are transition-metal-based materials, such as perovskites, spinel oxides, and pyrochlores, or carbon-based materials, such as metal–organic frameworks and covalent organic frameworks. 3D materials are also obtained through the in situ growth of freestanding electrode material over 2D-conducting substrates, such as graphene, carbon cloth, covalent organic framework stainless steel mesh, Ni foam, and copper foam. Thus, 3D materials have displayed excellent oxygen electrocatalysis for zinc–air batteries.