N/S-Doped Hierarchical Porous Bamboo Carbon Fibers with Ultra-Large Surface Area and Highly Exposed Active Sites for Flexible Zinc-Air Battery

Abstract

Facile mass transport channel and accessible active sites are crucial for binder-free air electrode catalysts in rechargeable flexible zinc-air battery (ZAB). Herein, a ZnS/NH ₃ dual-assisted pyrolysis strategy is proposed to prepare N/S-doped hierarchical porous bamboo carbon cloth (HP-NS-BCC) as binder-free air electrode catalyst for ZAB. BCC fabric with abundant micropores is firstly used as flexible carbon support to facilitate the heteroatom-doping and construct the hierarchical porous structure. ZnS nanospheres and NH ₃ activization together facilitate the electronic modulation of carbon matrix by N/S-doping and optimize the macro/meso/micropores structure of carbon fibers. Benefiting from the highly-exposed N/S-induced sites with enhanced intrinsic activity, the optimized mass transport of biocarbon fibers, as well as the ultra-large specific surface area of 2436.1 m ²·g ^–1, the resultant HP-NS-BCC catalyst exhibits improved kinetics for oxygen reduction/evolution reaction. When applied to rechargeable aqueous ZABs, it achieves a significant peak power density of 249.1 mW·cm ⁻². As binder-free air electrode catalyst, the flexible ZAB also displays stable cycling over 500 cycles with a minimal voltage gap of 0.42 V, showcasing promising applications in flexible electronic devices.

Keywords

Hierarchical porous structure / Bamboo carbon fibers / N/S-doped catalyst / Flexible Zn-air batteries / Oxygen reduction reaction / Oxygen evolution reaction / Electrocatalysis / Catalytic activity

RIGHTS & PERMISSIONS

2024 SIOC, CAS, Shanghai, & WILEY-VCH GmbH