Facile preparation of nitrogen-doped carbon nanosheets from CO2 for potassium-ion storage

Abstract

Carbons have emerged as promising anode materials for potassium-ion batteries (PIBs) due to their apparent merits including stable physical/chemical properties, high electronic conductivity and cost-effectiveness. However, the application of carbons in PIBs is impeded by their narrow layer spacing, limited active sites, and tedious preparation routes. Herein, nitrogen-doped carbon nanosheets (NCNS) was synthesized by a rapid and concise combustion process in which carbon dioxide was captured as a precursor. The as-fabricated NCNS presents a uniform lamellar structure, enlarged surface area and efficient nitrogen-doping, which bestow it with effective ion/electron transport paths and abundant potassium storage sites. Benefitting from these merits in the microstructure, NCNS-12 demonstrate a higher capacity, an enhanced rate performance of 300 mA h g⁻¹ at 50 mA g⁻¹ and a fascinating cyclic stability of 120 mA h g⁻¹ after 4000 cycles at 500 mA g⁻¹. Evidence from storage mechanism analysis further confirms that the storage process of K⁺ is mainly controlled by surface-dominated capacitive behavior. Furthermore, because of the merits of NCNS-12, a full cell combined with a Prussian blue (PB) cathode manifests high energy density and power output (217.0 W h kg⁻¹/270.1 kW kg⁻¹). The design strategy proposed in this study not only provides a new opportunity for the fast and concise synthesis of carbon materials but also affords a valuable understanding of potassium storage.