Engineering solid–liquid-gas interfaces of single-atom cobalt catalyst for enhancing the robust stability of neutral Zn-air batteries under high current density

Abstract To simultaneously achieve high power density and robust stability under high current density for neutral Zn-air batteries (ZABs), it is significant yet still remains challenging for the rational design of advanced air–cathode electrocatalyst with fast electron transfer, rapid oxygen/electrolyte transport and timely water removal. Herein, we synthesized the single Co atoms embedded in sandwich-like multimodally porous N-doped dual-carbon architecture (denoted as the NMCS-rGO-Co) via a facile self-assembly method and subsequent pyrolysis strategy. By taking advantage of abundant Co-N4 active sites and the optimized multimodally porous structure, the obtained NMCS-rGO-Co catalyst possesses stable three-phase reaction interfaces (catalysts, electrolyte and oxygen), which could be beneficial to simultaneously achieving fast electron transfer, accelerated oxygen/electrolyte diffusion and timely water removal. In response, the NMCS-rGO-Co catalyst displays excellent ORR performance in neutral electrolyte. More importantly, the NMCS-rGO-Co-based neutral ZABs exhibit the robust stability accompanied with the continuously discharging for 36 h under high current density of 50 mA cm−2. This is the first time to rationally design efficient catalysts for achieving the long-term stability of neutral ZABs at high current density from the perspective of constructing stable three-phase interfaces. This work also sheds new lights on the development of neutral ORR catalysts for the application of sustainable energy conversion technologies.