High-performance potassium ion capacitors enabled by hierarchical porous, large interlayer spacing, active site rich-nitrogen, and sulfur Co-doped carbon

Potassium ion hybrid capacitors (PIHCs) have drawn considerable attention due to the fact that they can combine the merits of high energy density of potassium ion batteries (KIBs) and high power density of supercapacitors. However, the sluggish kinetics caused by the large radius of K+ largely hinder the practical application of PIHCs. In this work, we report a nitrogen and sulfur co-doped 3D hierarchical porous carbon (N, S-3DHPC-600) as an anode for KIBs, possessing boosted potassium storage performance in terms of high reversible capacity, superior durability and rate capability. This N, S-3DHPC-600 electrode provides a large surface area, highly interconnected micro/mesoporosity, high ratio of pyridinic N/pyrrolic N and enlarged interlayer distance, which could promote the fast intercalation/deintercalation of K+, improve the surface charge capacity and maintain the structural stability of electrode material. As expected, a PIHCs device is constructed by employing this N, S-3DHPC-600 as an anode and AC-800 as a cathode, delivering exceptionally high energy/power densities (130.6 Wh Kg−1/16800W Kg−1), as well as a long cycle life (86.8% capacity retention after 5000cycles).