Synergistically catalytic enhanced of Zn–N/Co–N dual active sites as highly efficient and durable bifunctional electrocatalyst for rechargeable zinc-air battery

Abstract

The theoretical energy density, stability and cost of Zn-air batteries (ZAB) are far inferior to the most advanced lithium-ion batteries due to the irreversibility of zinc electrodes and sluggish electrocatalytic performance of oxygen reduction (ORR) and oxygen evolution (OER) processes. Herein, we designed a simple strategy to fabricate a quaternary Zn–Co–N–S co-doped tubular carbon (0.3-Zn-Co-N/S–C) via direct pyrolysis of various mixtures of precursors. The high porosity of 3D nanostructure not only provides better mass transfer but also offers a large number of active sites thereof superior ORR and OER performances. As a result, the rechargeable ZAB fabricated using optimized 0.3-Zn-Co-N/S–C as cathode exhibited a higher open-circuit voltage, stable discharge rate, and better reversibility, even exceeding the state-of-the-art Pt/C catalyst in alkaline solution. The catalytic mechanism indicates that the synergistic effect of Co metal nanoparticles, Co–N/Zn–N active sites, and the high-yield of N/S-doped tubular carbon dominate the outstanding catalytic performance.