Nitrogen-doped carbon derived from pre-oxidized pitch for surface dominated potassium-ion storage

Graphitic material has captured tremendous attentions as anode material for potassium ion batteries (PIBs). Nevertheless, the large radius of potassium-ions results in sluggish potassiation kinetics and huge volume expansion, leading to unsatisfying performance. Herein, a fabrication facile, cost-effective and high carbon yield nitrogen/oxygen co-doped amorphous carbon (NOC) with pitch and urea as precursors is reported. Pre-oxidation process is employed, maintaining the amorphous structure of pitch derived carbon against its soft carbon nature. The NOC electrode delivers reversible capacities of 347 (300th cycle) and 167 mAh g⁻¹ (1000th cycle) at 100 and 2000 mA g⁻¹, respectively. Rearrangement of graphene layers in short range benefits the structure stability against volume change. Kinetics analyses prove that surface-induced capacitive process dominates in K-ion storage mechanism, which contributes to the remarkable electrochemical performance. Pouch full cells were assembled, delivering a capacity of 316 mAh g⁻¹ at 100 mA g⁻¹. In view of the cost-effectiveness and electrochemical performance, this work offers a strategy for the fabrication of low-cost and high-performance PIB anode materials.