Fe3C encapsulated in N-doped carbon as potassium ion battery anode with high capacity and long-term cycling performance

Transition metal carbide is being used as an emerging high-capacity anode material for the next-generation potassium ion batteries (PIBs). Herein, a general method was introduced for the preparation of nanocomposites from metal–organic frameworks (MOFs) coated with ammonium ferric citrate. A novel composite material of Fe3C nanoparticles was designed and prepared by pyrolysis of MOF, and embedded in graphitic carbon as a PIB anode (Fe3C@MOF–C/N). The Fe3C particles were encapsulated in an N-doped carbon shell with a hierarchical porous carbon network. N-doped porous carbon exhibited a large specific surface area and abundant carbon edge defects, which led to the increase in the number of exposed active sites, facilitating the adsorption of potassium ions. As a result, the prepared carbon material shows high structural stability, electrical conductivity, and proton conductivity. As a PIB anode, Fe3C@MOF–C/N-1 shows a high capacity of 294 mAh g−1 over 1000 cycles at 200 mA g−1, revealing its potential application as carbon material in PIB anodes.