Promoted oxygen reduction performance enabled by Co/Cu nanoparticles encapsulated in carbon nanotubes for long-life flexible and rechargeable Zn–air batteries†

Rechargeable zinc–air batteries have been extensively studied as a potential solution for overcoming the challenges of energy crises and achieving sustainable development. The primary bottleneck of zinc–air batteries is the lack of efficient and low-cost dual-functional catalysts. In this study, we successfully prepared carbon nanotube-encapsulated bimetallic Co/Cu (Co/Cu_0.2@NC) catalysts that exhibit excellent ORR (E_1/2 = 0.838 V) and OER (overpotential of 322 mV at 10 mA cm⁻²) performances, exceeding those of the commercial RuO₂ and Pt/C catalysts. Furthermore, rechargeable liquid zinc–air batteries prepared using the Co/Cu_0.2@NC catalysts show a high power density (171.44 mW cm⁻²), a high open circuit voltage (1.485 V), and a long life with stability for 2400 cycles (or 400 h). More importantly, flexible zinc–air batteries prepared using this catalyst exhibit a peak power density of 70.8 mW cm⁻² and a superior stability for 480 cycles (or 80 h). This excellent dual-functional catalyst has great potential for zinc–air battery and other energy storage applications.