Electrolyte Salt Chemistry Enables 3D Nitrogen and Phosphorus Dual‐Doped Graphene Aerogels for High‐Performance Potassium‐Ion Batteries

Abstract Potassium‐ion batteries (PIBs) have attracted tremendous attentions for scalable electrical energy storage owing to the abundant K resources. Heteroatom co‐doped hard carbon is considered to be a reliable material to boost ion transport and provide active sites for reversible potassium storage. Herein, N/P dual‐doped 3D graphene aerogels (NPGAs) with hierarchical pores, enlarged interlayer distance, and high doping level are successfully synthesized, which exhibit outstanding electrochemical performance for PIBs. A detailed comparative study found that promoted coulombic efficiency, improved specific capacity (507 mAh g⁻¹ at 100 mA g⁻¹ after 100 cycles) and excellent cycle performance (106 mAh g⁻¹ at 5000 mA g⁻¹ after 3000 cycles) can be reached by replacing KPF₆ with potassium bis(fluorosulfonyl)imide (KFSI). Further kinetic analysis reveals that NPGAs present more capacitive behavior of K‐ion, low resistance, and fast K‐ion conductivity by virtue of the advanced solid electrolyte interphase (SEI) film formed in KFSI‐EC/DEC electrolyte. Ex situ XPS, SEM, and TEM all confirm a physical flexible, chemical stable, and inorganic SEI layer formed on the surface of the electrode. In general, this work promotes a deep understanding of the mechanism of potassium storage and provides more opportunities for practical PIBs.