Fe-Co-Ni ternary single-atom electrocatalyst and stable quasi-solidelectrolyte enabling high-efficiency zinc-air batteries

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-Nx)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-Nx catalyst,and the electrochemical,mechanical,and durability tests prove the superiority of the CD-PVA film.As a result,the FeCoNi-Nx-based rechargeable Zn-air battery delivers superior specific capacity(846.8 mAh·gZn-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.