Nitrogen-doped carbon fibers loaded with Co/Co2Mn3O8 alloy nanoparticles as bifunctional oxygen electrocatalysts for rechargeable zinc-air batteries

The lack of low-cost and high-activity bifunctional electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is an important factor restricting the massive application of rechargeable zinc-air batteries (ZABs). Herein, nitrogen-doped carbon fibers (NCFs) loaded with Co/Co2Mn3O8 alloy nanoparticles (Co/Co2Mn3O8@NCFs) were reported as a bifunctional oxygen electrocatalyst for rechargeable ZABs. The hierarchical porous structure of NCFs and strong synergetic coupling between Co/Co2Mn3O8 alloys and Co-Nx sites accelerated the kinetics of ORR reaction. The abundant lattice oxygen and N-doped sites promoted the efficient OER process. Benefiting from the above advantages, a rechargeable ZAB assembled with Co/Co2Mn3O8@NCFs delivered an excellent energy density of 968.10 Wh kg−1 (normalized to the mass of consumed zinc) and outstanding stable cyclability (steady cycle charge and discharge at 10 mA cm−2 for 120 h), surpassing state-of-the-art Pt/C catalyst (830.86 Wh kg−1/75 h). This study demonstrated the potential value of Co/Co2Mn3O8 alloys in energy conversion and storage. [Display omitted] •The unique core-shell structure facilitates the exposure of active sites and the ordered conduction of electrons.•The electron transition between different valence metals can modulate the adsorption activity of oxygen at the site center.•The addition of Mn can inhibit H2O2 generation and improves the stability of the catalyst.