Accordion-Like Carbon with High Nitrogen Doping for Fast and Stable K Ion Storage

Potassium ion battery (PIB) is a potential candidate for future large-scale energy storage. A key challenge is that the (de)potassiation stability of graphitic carbon anodes is hampered by the limited (002) interlayer spacing. Amorphous carbon with a hierarchical structure can buffer the volume change during repeated (de)potassiation and enable stable cycling. Herein, a direct pyrolysis approach is demonstrated to synthesize a highly nitrogen-doped (26.7 at.%) accordion-like carbon anode composed of thin carbon nanosheets and a turbostratic crystalline structure. The hierarchical structure of accordion-like carbon is endowed by a self-assembly process during pyrolysis carbonization. The hierarchical nitrogen-doped accordion structure enables a high reversible capacity of 346 mAh g−1 and superior cycling stability. This work constitutes a general synthesis methodology that can be used to prepare hierarchical carbon anodes for advanced PIBs.