High-throughput fabrication of 3D N-doped graphenic framework coupled with Fe₃C@porous graphite carbon for ultrastable potassium ion storage

Graphenic materials are deemed to be a promising anode material for potassium-ion battery (KIBs) due to its exceptional electronic conductivity, high surface area, light weight nature and chemical stability, while the high cost and low reversible capacity limit its practical application. Herein, we design a three-dimensional (3D) N-doped graphenic framework coupled with Fe₃C@porous graphite carbon core-shell structures (Fe₃C@PGC-NGF) by a cheap and high-throughput chemical blowing strategy. This 3D graphenic framework spatially sustained by the graphitic struts has the capability to retain its integral structure during charge/discharge process. It should be emphasized that the Fe₃C acts as an efficient catalyst in two stages: the formation of PGC wrapped around Fe₃C during the synthetic process and the reversible formation/dissolution of solid electrolyte interface (SEI) film during cycling. More importantly, the PGC can confine the active Fe₃C during K⁺ intercalation/deintercalation to avoid its pulverization and simultaneously increase the electronic conductivity. Thus, the Fe₃C@PGC-NGF electrode exhibits an exceptional cycle performance of 10,000 cycles with high capacity retention of 155 mA h g⁻¹ at 1000 mA g⁻¹ and high initial Coulombic efficiency of 73% in KIBs.