The non-noble metal (Fe, Co, Ni, etc.) catalysts possess promising potential to replace noble metals (e.g., Pt, Ru, Ir, etc.) as catalysts for oxygen electrocatalysis. Up to now, various mono- and dual-single-atom catalysts have been fabricated, though it is still challenging to synthesise ternary single-atom catalysts due to the difference of interaction forces between different metal ions (Fe, Co, Ni, etc.) and ligands. Here, we report a Fe-Co-Ni ternary single-atom catalyst (FeCoNi-N_x) derived from a zeolitic imidazolate frameworks (ZIF) precursor as an efficient oxygen electrocatalyst, and an optimised flexible casting-drying polyvinyl alcohol (CD-PVA) film as a quasi-solid electrolyte host, for high-efficiency solid-state Zn-air batteries. The aberration-corrected HAADF-STEM and EELS spectrum confirm the co-existence of Fe, Co and Ni single atoms in the FeCoNi-N_x catalyst, and the electrochemical, mechanical, and durability tests prove the superiority of the CD-PVA film. As a result, the FeCoNi-N_x-based rechargeable Zn-air battery delivers superior specific capacity (846.8 mAh·g_Zn^–1) and power density (135 mW·cm^–2) in aqueous electrolyte, as well as an over 60 mW·cm^–2 power density in quasi-solid electrolyte. As a result, the quasi-solid-state Zn-air battery with a small area of only 2 cm² is able to charge a mobile phone, which outperforms all the reported devices to date.

The paper discusses the progress and commercialization of binders for energy storage applications, such as batteries. It explains the role of binders in holding together active materials and current collectors, and highlights the challenges associated with conventional organic solvents in binders. The potential of aqueous binders is introduced as a cost-effective and environmentally friendly alternative. The advantages and limitations of different types of binders are discussed, and the importance of binder selection for optimal battery performance is emphasized. The current state of commercialization of binders is reviewed, and the need for collaboration between researchers, manufacturers, and policymakers to develop and promote environmentally friendly and cost-effective binders is emphasized. The paper concludes by outlining future directions for research and development to further improve the performance and commercialization of binders, while addressing limitations such as lack of standardization, high cost, and long-term stability and reliability.