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Driven by the intensified demand for energy storage systems with high-energy density and safety, all-solid-state zinc (Zn) air batteries have drawn extensive attentions. However, the development of non-precious metals with high catalytic activity as the air electrode is still a big challenge. In this work, we realize the large-scale fabrication of single-crystal CoO nanorods with high active facets and abundant oxygen vacancies in-situ on conductive substrate, which exhibits superior electrocatalytic activity in both oxygen reduction reaction and oxygen evolution reaction. The all-solid-state Zn-air batteries assembled with such free-standing CoO NRs show low charge/discharge overpotentials, a high energy density and a high cyclic stability. Our work indicates that the rational structure design of catalysts can pave a new route to next generation efficient and durable electrochemical devices.

Zinc-air batteries offer a possible solution for large-scale energy storage due to their superhigh theoretical energy density, reliable safety, low cost, and long durability. However, their widespread application is hindered by low power density. Herein, a multiscale structural engineering of Ni-doped CoO nanosheets (NSs) for zinc-air batteries with superior high power density/energy density and durability is reported for the first time. In micro- and nanoscale, robust 2D architecture together with numerous nanopores inside the nanosheets provides an advantageous micro/nanostructured surface for O2 diffusion and a high electrocatalytic active surface area. In atomic scale, Ni doping significantly enhances the intrinsic oxygen reduction reaction activity per active site. As a result of controlled multiscale structure, the primary zinc-air battery with engineered Ni-doped CoO NSs electrode shows excellent performance with a record-high discharge peak power density of 377 mW cm-2 , and works stable for >400 h at 5 mA cm-2 . Rechargeable zinc-air battery based on Ni-doped CoO NSs affords an unprecedented small charge-discharge voltage of 0.63 V, outperforming state-of-the-art Pt/C catalyst-based device. Moreover, it is shown that Ni-doped CoO NSs assembled into all-solid-state coin cells can power 17 light-emitting diodes and charge an iPhone 7 mobile phone.