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

Abstract

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 Fe 3 C nanoparticles was designed and prepared by pyrolysis of MOF, and embedded in graphitic carbon as a PIB anode (Fe 3 C@MOF–C/N). The Fe 3 C 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, Fe 3 C@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. Fe 3 C in the formation of nanocrystallization is encapsulated in the separate N-doping carbon, and shows remarkably enhanced electrochemical potassium ion storage performance. • ZIF-8 derived porous carbon core provide space for s physical adsorption of the PIBs. • Capacity of 294 mAh g −1 is remained for Fe 3 C@MOF–C/N-1 at 200 mA g −1 after 1000 cycles. • Fe 3 C in the formation of nanocrystallization is encapsulated in the separate N-doping carbon. • The Fe 3 C@MOF–C/N-1 anodes exhibit enhanced cyclic stability and rate performance.