Modification of Porous N‐Doped Carbon with Sulfonic Acid toward High‐ICE/Capacity Anode Material for Potassium‐Ion Batteries

Abstract Among anode materials for potassium‐ion batteries (PIBs), carbon‐based materials attract extensive attention due to their abundant material resources, low cost, high surface capacity, and excellent electrical conductivity. However, carbon‐based materials always display a low initial coulombic efficiency (ICE), which greatly hinders the full utilization of the battery capacity and energy density. Moreover, the slow dynamic process and the large volume expansion during intercalation result in poor cyclic stability. In this work, a sulfonic acid modified porous N ‐doped carbon (SA‐NC) is prepared as an anode for PIBs. This SA‐NC material provides abundant migration channels and active potassium storage sites with K + adsorption energy as low as −1.752 eV, which promote rapidly reversible surface adsorption/desorption capacitance storage of K + , and improve the potassium storage performance and the ICE of the electrode simultaneously. The material exhibits outstanding performance with high reversible initial charging specific capacity (793 mAh g –1 at 0.05 A g –1 current density, 90% capacity retention after 80 cycles), high initial coulomb efficiency (68.21% at 0.1 A g –1 ), and long‐time hyper‐stable cycling stability (288 mAh g –1 after 2000 cycles at 2 A g –1 ), which show outstanding performance in all aspects and is at the leading level in carbon anode materials.