Reconstructed Wood Carbon Aerogel with Single-Atom Sites for Flexible Zn–Air Batteries

Abstract

Single-atom catalysts (SACs) have become vital air cathodes for metal-air batteries, but fabricating monolithic SACs with high catalytic activity and mechanical strength is currently lacking. Herein, an all-natural wood carbon aerogel with single-atom sites is reconstructed via modulating the multi-interactions within lignocellulosic components. Cellulose nanofiber (CNF) constitutes an oriented scaffold via physical interweaving and strong electrostatic repulsion, while lignosulfonate, acting as a multifunctional bioligand, coordinates with metal ions and forms hydrogen bonds with CNF to prevent the agglomeration of adjacent metal atoms. The resulting carbon aerogel features a biomimetic channel-ordered microstructure with M-N₄ active sites (M = Cu, Fe, and Co), leading to outstanding mechanical elasticity and oxygen reduction and evolution activities with a half-wave potential of 0.881 V. Therefore, the SA-Cu@NCA-based aqueous Zn-air battery (ZAB) exhibits a high specific capacity of 779.3 mA h g^-1 and long-term stability, while the flexible ZAB with SA-Cu@NCA as an integrated cathode delivers a high specific capacity and impressive operating stability even under harsh structural deformations. This study presents a viable approach for the sustainable production of flexible SACs for wearable and portable electronics.