Low‐Temperature Carbonized N/O/S‐Tri‐Doped Hard Carbon for Fast and Stable K‐Ions Storage

Abstract Hard carbon stands out as one of the premier anodes for potassium‐ion batteries (PIBs), celebrated for its cost‐effectiveness, natural abundance, and high yield. Yet, its performance in PIBs remains subpar due to slow kinetics, a result of the large ionic radius of K‐ions. Herein, a unique lamellar N/O/S‐tri‐doped hard carbon (NOSHC) has been developed at an impressively low pyrolysis temperature of 500°C, showcasing a distinct “slope‐dominated” characteristic. NOSHC delivers superior rate performance with a dominant surface‐driven capacitive contribution (71.6% at a scan rate of 0.5 mV s −1 ), maintaining a robust reversible specific capacity of 125 mAh g −1 (half its peak) even at 5 A g −1 . Its stability is equally commendable, as it sustains a substantial specific capacity of 265 mAh g −1 after 100 cycles at 0.1 A g −1 and retains 210 mAh g −1 post‐1000 cycles at 1 A g −1 . Moreover, NOSHC undergoes continuous activation via potassiation/depotassiation during cycling. Rich heteroatom doping introduces a plethora of defects and vacancies, creating abundant active sites. The distinct lamellar structure, featuring minimal pores, optimizes K‐ions transport by shortening the diffusion length. This study unveils the potential of enhancing hard carbon anodes for PIBs by harnessing a low carbonization temperature approach.