Nitrogen doping induces carbon micro-defect to improve potassium storage properties

Potassium ion hybrid capacitors (PIHCs) are increasingly attracting much interest for large-scale energy storage, valued for their affordability and resilience, even under harsh conditions such as high temperature, low temperature, and mechanical Stress. Nevertheless, their advancement is hindered by the intrinsically sluggish kinetics and the lack of suitable anode materials. Herein, the nitrogen doping strategy is used to produce micro-defect, increasing the likelihood of exposing large edge active sites, which can realize the improved potassium ion storage kinetics. More importantly, the electrical characterizations and density functional theory calculation are carried out to reveal the consequence of faulty structure and heteroatom doping. Consequently, after 200 cycles at 0.05 A g⁻¹, the electrode achieves a long cycle lifetime and high capacity (354.4 mA h g⁻¹). Impressively, PIHCs made with an N doped carbon anode demonstrated remarkable energy density of 116.5 Wh kg⁻¹ at a power density of 800 W kg^–1, together with outstanding cycling stability (92.5 % capacity retention over 1000 cycles). This study unveils a new insight about the effects of defects and fast reaction kinetics in doped carbon materials affect potassium ion storage.