Robust and flexible 3D integrated FeNi@NHCFs air electrode for high-performance rechargeable zinc-air battery

Designing bifunctional oxygen reduction/evolution (ORR/OER) catalysts with high activity, robust stability and low cost is the key to accelerating the commercialization of rechargeable zinc-air battery (RZAB). Here, we propose a template-assisted electrospinning strategy to in situ fabricate 3D fibers consisting of FeNi nanoparticles embedded into N-doped hollow porous carbon nanospheres (FeNi@NHCFs) as the stable binder-free integrated air cathode in RZAB. 3D interconnected conductive fiber networks provide fast electron transfer pathways and strengthen the mechanical flexibility. Meanwhile, N-doped hollow porous carbon nanospheres not only evenly confine FeNi nanoparticles to provide sufficient catalytic active sites, but also endow optimum mass transfer environment to reduce diffusion barrier. The RZABs assembled by FeNi@NHCFs as integrated air cathodes exhibit outstanding battery performance with high open-circuit voltage, large discharge specific capacity and power density, durable cyclic stability and great flexibility. Thus, this work brings a useful strategy to fabricate the integrated electrodes without using any polymeric binders for metal air batteries and other related fields. Graphical abstract: (Figure presented.)