Enhanced Mass Transfer in Flexible Electrodes of Open-Pore Cobalt Disulfide Nanosheets Supported on Sulfur-Doped Carbon Fibers for Efficient Zinc–Air Batteries

Robust integration of free-standing electrodes with efficient mass transport structuring represents a cornerstone for flexible devices. Herein, this work employs facile dual-step electrodeposition-sulfurization on cotton-derived carbon substrate to develop a self-supporting electrode. The resulting open-pore CoS 2 nanosheets on S-doped cotton-derived carbon fiber (CoS 2 -S-CCF) achieve Co−S−C interfacial bonding via in-situ sulfur-induced self-assembly/doping, synergistically enhancing mass/charge transfer. The CoS 2 -S-CCF thus delivers exceptional oxygen evolution reaction performance (overpotential: 332 mV@10 mA·cm -2 ; Tafel slope: 65.1 mV·dec -1 ) and enhanced oxygen reduction reaction activity (half-wave potential: +0.18 V). When deployed in flexible zinc-air batteries, this self-supporting electrode delivers a peak power density of 33.3 mW·cm -2 and stable cycling exceeding 500 cycles, markedly outperforming slurry-based Pt/C+RuO 2 counterparts failing within 400 cycles. Pivotal advantages include the CoS 2 -substrate open-pore network enabling enhanced mass transport beyond dopant effects, binder-free design eliminating interfacial loss, and Co−S−C bonding assuring conductivity retention under deformation. This work provides novel design principles for highly durable free-standing flexible electrodes with optimized mass transfer.