Cage compound precursor-derived Sb/Sb2O4/Fe3C nanocomposite anchored on reduced graphene oxide as an anode for potassium ion batteries

The abundant reserves of potassium in the earth's crust and its low K/K+ redox potential (−2.93 V) make potassium ion batteries (PIBs) a potential candidate for next-generation ion batteries. Antimony (Sb) has a high theoretical specific capacity for PIBs, but the pulverization of Sb-based electrodes severely shortens their cycle lifetimes and hinders their use in PIBs. Here, a cage compound precursor-derived Sb/Sb2O4/Fe3C nanocomposite anchored on reduced graphene oxide with uniform distribution is fabricated and used as an anode for PIBs. Benefitting from the high capacity of Sb/Sb2O4 and the catalyst Fe3C that can promote the reversible dissolution of SEI film, the anode delivers a reversible specific capacity of 234 mA h g−1 at 500 mA g−1 over 280 cycles and a long-term cycling performance of 108 mA h g−1 at 2000 mA g−1 over 1244 cycles.