Sulfur/Nitrogen Co-Doped In-Plane Porous Carbon Nanosheets as Superior Anode of Potassium-Ion Batteries

Carbonaceous materials are regarded as prospective anode candidates of potassium-ion batteries. However, the rate capability and cycling stability of classic carbon materials are still far from satisfactory. Herein, we exploit a facile and low-cost strategy to enable the precise synthesis of sulfur/nitrogen co-doped in-plane porous carbon nanosheets with fishnet-shaped microstructure (SN-CNSs). The well-designed in-plane porous structure and the interconnected carbon flake network can accelerate the diffusion of potassium ions, alleviate volume expansion, and provide sufficient active sites. As a result, the SN-CNSs deliver an impressively reversible capacity of 248 mAh g(-1) at a current density of 1 Ag-1 after 4500 cycles, and an excellent rate capacity of 137.3 mAhg(-1) after 4000 cycles under 5 Ag-1. Density functional theory (DFT) calculations further verify the advantage of S/N co-doping in the adsorption/diffusion of K-ion in SN-CNSs materials. Such an excellent performance shows that SN-CNSs possess a great potential to be a superior anode of potassium-ion batteries.