Innovative Air Cathode with Ni-Doped Cobalt Sulfide in Highly Ordered Macroporous Carbon Matrix for Rechargeable Zn-Air Battery

초록

To realize the practical application of rechargeable Zn-Air batteries (ZABs), it is imperative to develop a non-noble metal-based electrocatalyst with high electrochemical performance for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, Ni-doped Co9S8 nanoparticles dispersed on an inverse opal-structured N, S co-doped carbon matrix (IO & horbar;NixCo9-xS8@NSC) as a bifunctional electrocatalyst is presented. The unique 3D porous structure, arranged in an inverse opal pattern, provides a large active surface area. Also, the conductive carbon substrate ensures the homogeneous dispersion of NixCo9-xS8 nanocrystals, preventing aggregation and increasing the exposure of active sites. The introduction of heteroatom dopants into the Co9S8 structure generates defect sites and enhances surface polarity, thereby improving electrocatalytic performance in alkaline solutions. Consequently, the IO & horbar;NixCo9-xS8@NSC shows excellent bifunctional activity with a high half-wave potential of 0.926 V for ORR and a low overpotential of 289 mV at 10 mA cm-2 for OER. Moreover, the rechargeable ZAB assembled with prepared electrocatalyst exhibits a higher specific capacity (768 mAh gZn-1), peak power density (180.2 mW cm-2), and outstanding stability (over 160 h) compared to precious metal-based electrocatalyst. The Ni-doped Co9S8 nanoparticles dispersed on an inverse opal-structured N, S co-doped carbon matrix (IO & horbar;NixCo9-xS8@NSC) are rationally designed using a self-sacrificial template strategy. The prepared electrocatalyst is employed as an efficient bifunctional electrocatalyst for rechargeable Zn-air batteries, exhibiting superior specific capacity, power density, and long-term cyclability compared with the battery assembled with a precious metal-based electrocatalyst. image

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