Influence of P doping on Na and K storage properties of N-rich carbon nanosheets

Nitrogen or phosphorus doping is a commonly used method to ameliorate the electrochemical properties of carbonaceous material. In this study, nitrogen-rich carbon nanosheets are first prepared and then annealed with NaH2PO4 to synthesize phosphorus doping nitrogen-rich carbon nanosheets. Two obtained materials are utilized as anodes of sodium-ion batteries and potassium-ion batteries, revealing that phosphorus doping can improve sodiation capacity (247.9 vs. 175.1 mA h g−1) and lower potassiation capacity (207.2 vs. 242.6 mA h g−1). To explore the inner reason for this phenomenon, Na+ and K+ diffusion coefficients are surveyed through galvanostatic intermittent titration technique, showing that the electrode with large ion diffusion coefficient delivers a large capacity. This work provides some use for reference in introduction of heteroatoms to carbonaceous anode materials of sodium-ion batteries and potassium-ion batteries.