Unveiling the Energy Storage Behavior and Enhanced Absorption Kinetics of Sulfur Functionalized Nitrogen‐Doped Hierarchical Porous Carbon Nanosheets for Efficient Alkali Metal Ion Storage

ABSTRACT Carbonaceous materials have obtained significant concern due to their low cost and physicochemical stability merits, whereas the comparatively low electrochemical capacity and tardiness dynamics characteristics hinder rapid and sustainable development. Herein, a novel strategy involving the manipulation of sulfur and nitrogen is devised to enhance the reaction dynamics and pseudocapacitance characteristics of carbon nanosheets (S&N‐CNS), leading to a superior carbonaceous anode for both potassium (K) and sodium (Na) ion storage. Thus, the well‐designed S&N‐CNS could demonstrate elevated electrochemical performance, including a high specific capacity of 433.9/523.7 mAh/g at 0.1/0.2 A g −1 and a stable cycling life over 2000/3000 cycles at 5.0 A g −1 for K + /Na + storage, respectively. The promoted performance is benefited by the increased charge transfer capacity, active/defect sites, and ion transport dynamics, as confirmed by various electrochemical measurements and theoretical simulation results. Furthermore, the underlying application is conducted by assembling a potassium ion hybrid capacitor with S&N‐CNSs and an activated carbon (AC) electrode, which could contribute a high energy density of 124.0 Wh kg −1 at a power density of 165.3 W kg −1 and super cycling life over 4000 cycles. This research contributes to advancing the exploration of carbon anodes and fostering the development of alkali metal ion batteries.