Potassium-ion batteries with novel N, O enriched corn silk-derived carbon as anode exhibiting excellent rate performance

Abstract Recently, several defect control routes benefit the development of potassium ion batteries (PIBs) by significantly ameliorating K+ diffusion kinetic and volume expansion in the reaction. However, formation of defects in nanostructure always requires delicate control technology and high cost. In this work, biomass corn silk is applied to serve as inexpensive carbon precursor to fabricate porous carbon microstructure via hydrothermal treatment and one-step carbonization. Facile regulation of carbonization temperature not only adjusts the characteristic of pore structure, but also affects the degree of graphitization. Moreover, the residual N and O element are apt to be doped into the porous carbon structure, which can significantly promote the conductivity and reaction activity. An optimized annealing temperature of 750 °C endows such N, O dual-doped porous carbon (NOPC-750) structure with rich electrolyte accessible sites, high conductivity and suitable structure for rapid K+ diffusion. Employed as PIBs anode, NOPC-750 presents a high reversible capacity of 309.8 mAh g−1 at 0.1 A g−1 and high rate performance (retain 105.8 mAh g−1 even at 20 A g−1). The in-depth electrochemical potassium storage mechanism is elaborated, which mainly relies on the capacitance-controlled (surface-driven) contribution, further revealing the rapid reaction kinetics.