Multiscale Structural Engineering of Ni-Doped CoO Nanosheets for Zinc-Air Batteries with High Power Density.

Abstract

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.