Interconnected honeycomb-like carbon with rich nitrogen/sulfur doping for stable potassium ion storage

Abstract

Carbonaceous materials are selected as promising anodes for potassium-ion batteries (PIBs). Nevertheless, it is still a significant bottleneck to fabricate an ideal carbonaceous material with impressive rate capability and cycling performance due to the sluggish kinetics of K+. Herein, a hard template-assisted strategy is reported for designing a class of rhodanine-derived nitrogen/sulfur co-doping honeycomb-like carbons as anodes for PIBs. The characteristics, including high nitrogen/sulfur content (6.28/3.3 at%), high surface area (560 m2 g−1), and interconnected honeycomb-like structure, play significant roles in boosting potassium ion storage by offering more electroactive sites and shorting the ion transfer distance, resulting in ultrahigh reversible capacity of 443.3 mA h g−1 at 100 mA g−1, exceptional rate capability (182.5 mA h g−1at 10 A g−1), and superior cyclability (97% retention ratio at 2 A g − 1 over 1000 cycles). Moreover, the electrochemical kinetic analysis manifests the fast capacitive-dominated potassium storage mechanisms. The fabricated potassium ion capacitor delivers a promising energy and power density (76.8 W h kg−1 and 10,413.7 W kg−1)), and simultaneously ultra-long lifespan (∼91% capacity retention over 2000 cycles). Such a work highlights that structure engineering coupled with doping engineering could effectively enhance K+ adsorption, providing a facile pathway of material design for high-performance PIBs.