Facile Fabrication of Nitrogen-Doped Porous Carbon as Superior Anode Material for Potassium-Ion Batteries

Potassium-ion batteries (PIBs), using carbon materials as the anode, are regarded as a promising alternative to lithium-ion batteries owing to the feasible formation of stage-1 potassium intercalation compounds (KC₈). However, due to the large radius of the potassium ion, graphite-based electrodes still suffer poor rate capability and insufficient cycling life. In this work, a hierarchically nitrogen-doped porous carbon (NPC) is reported for the first time. The NPC electrode delivers a high reversible capacity of 384.2 mAh g⁻¹ after 500 cycles at a current density of 0.1 A g⁻¹ and an outstanding rate capability of 185 mAh g⁻¹ at 10.0 A g⁻¹, which surpasses most of the reported carbonaceous electrodes in PIBs. The excellent performance can be ascribed to the surface-driven behavior dominated K-storage mechanism, which is verified by quantitative kinetics analysis. Theoretical simulation results further illuminate the enhanced K affinity in N-doped active sites, which accounts for the superior rate performance of the NPC electrode. In addition, galvanostatic intermittent titration technique measurements further quantify the diffusion coefficient of K ions. Considering the superior electrochemical performance of the electrode and comprehensive investigation of the K storage mechanism, this work can provide fundamental references for the subsequent research of potassium-ion batteries.