A Highly Durable Zinc-Air Battery from Directly Integrated FexNC@NiFe(OH)x Bifunctional Catalyst

Abstract

<p>Rechargeable zinc-air batteries (ZABs) hold great promise for energy storage and conversion due to their high theoretical energy density, cost-effectiveness, and inherent safety. However, progress is constrained by sluggish oxygen electrocatalysis and instability at the air cathode. To address such issues, we resort to a directly integrated pseudo-3D composite electrocatalyst based on carbon cloth, on which Fe/Fe<small>₃</small>C- and N- co-doped carbon nanotubes are directly induced and then used to further intercalate NiFe hydroxide clusters, Fe<small>_<em>x</em></small>NC@NiFe(OH)<small>_<em>x</em></small>. This hierarchical electrocatalyst shows enhanced oxygen electrocatalysis (Δ<em>E</em> is 636 mV), rendering high efficiency and durability of ZABs. Such improvement can be attributed to the rationally integrated pseudo-3D structure with high conductivity, high density of active sites, interconnected porosity, and well-bonded components for accelerating electron transfer and ion diffusion while ensuring structural integrity. Moreover, the hierarchical structure increases the electrochemical surface area with superior surface hydrophilicity. As a result, the composite electrocatalyst shows great potential as a binder-free air electrode, as demonstrated in a rechargeable ZAB of a high power density of 85.1 mW cm<small>⁻²</small> and a long period of operation beyond 2000 cycles (350 h) without notable degradation, outperforming noble metal electrodes.</p><p><img src="https://pubs.rsc.org/en/Image/Get?imageInfo.ImageType=GA&imageInfo.ImageIdentifier.ManuscriptID=D2QI02564G&imageInfo.ImageIdentifier.Year=2023" alt="Graphical abstract: A highly durable zinc-air battery from a directly integrated FexNC@NiFe(OH)x bifunctional catalyst">​​​​​​​</p>