Amorphous carbon with N-S bond active center for enhanced capacitive contribution of potassium-ion batteries

Carbon materials have great potential in achieving excellent potassium-ion batteries (PIBs), while the low theoretical capacity of carbon materials limits the application of potassium ion batteries. Here, we reported an amorphous porous carbon with rich N-S bonds (N-S/C) by simple self-assembly possess and pyrolysis possess. The prepared N-S/C material possesses plentiful N-S bonds, which can act as active center to enhance the electrochemical capacity and accelerate transport dynamics. In addition, abundant porous structure can increase the contact area between electrode materials and electrolyte to shortens the diffusion path of ion transport, thereby improving the rate performance. As PIBs anodes, the N-S/C material exhibits a markedly enhanced reversible capacity of 389 mAh g−1 at 50 mA g−1, excellent cycling stability (188.8 mAh g−1 at 500 mA g−1 after 1000 cycles) and rate performance (105 mAh g−1 at 2 A g−1). Importantly, the in-situ Raman unravels a reversible mechanism that intercalation/deintercalation of K+ into/from the N-S/C, and the electrochemical analysis shows the N-S bond can improve the capacitive activity and enable fast kinetics toward superior K+-storage. These results demonstrate a promising carbonaceous anode material for PIBs and may provide guidance for designing of electrode materials of PIBs.