Novel Hydrogel-Derived Bifunctional Oxygen Electrocatalyst for Rechargeable Air Cathodes.

Fu, Gengtao; Chen, Yifan; Cui, Zhiming; Li, Yutao; Zhou, Weidong; Xin, Sen; Tang, Yawen; Goodenough, John B · Nano Lett · 2016

basic_science · Level V

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Abstract

The commercialization of Zn-air batteries has been impeded by the lack of low-cost, highly active, and durable catalysts that act independently for oxygen electrochemical reduction and evolution. Here, we demonstrate excellent performance of NiCo nanoparticles anchored on porous fibrous carbon aerogels (NiCo/PFC aerogels) as bifunctional catalysts toward the Zn-air battery. This material is designed and synthesized by a novel K<sub>2</sub>Ni(CN)<sub>4</sub>/K<sub>3</sub>Co(CN)<sub>6</sub>-chitosan hydrogel-derived method. The outstanding performance of NiCo/PFC aerogels is confirmed as a superior air-cathode catalyst for a rechargeable Zn-air battery. At a discharge-charge current density of 10 mA cm<sup>-2</sup>, the NiCo/PFC aerogels enable a Zn-air battery to cycle steadily up to 300 cycles for 600 h with only a small increase in the round-trip overpotential, notably outperforming the more costly Pt/C+IrO<sub>2</sub> mixture catalysts (60 cycles for 120 h). With the simplicity of the synthetic method and the outstanding electrocatalytic performance, the NiCo/PFC aerogels are promising electrocatalysts for Zn-air batteries.