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

Abstract

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 A g−1 after 4500 cycles, and an excellent rate capacity of 137.3 mAh g−1 after 4000 cycles under 5 A g−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.

Recycled Graphite from Spent Lithium-Ion Batteries as a Conductive Framework Directly Applied in Red Phosphorus-Based Anodes

“…The capacitive contribution rates were determined to be 46.8, 50.4, 61.1, 68.9, and 70.6% at scan rates of 0.1, 0.2, 0.4, 0.6, and 1 mV s –1 , respectively (Figure f). The high capacitive contribution rate promotes long-term stability and rate performance …”

“…The high capacitive contribution rate promotes long-term stability and rate performance. 53 The electrochemical performances of the RGE and RGE/RP electrodes were compared (Figure 5a). In terms of cycling performance, the RGE electrode demonstrated a stable cycling performance at 0.2 A g −1 with minimal capacity decrease, which is comparable to that of commercial graphite (Figure S5).…”

New perspectives on the multianion approach to adapt electrode materials for lithium and post-lithium batteries

“…From DFT calculations, Li et al found that sulfur/nitrogen co-doping in carbon nanosheets increases their attraction for potassium. 131 According to Ling et al, the larger cations are inserted at higher voltages into iron hexacyanoferrate, and the migration of the larger cations is slower. 176 The ionic radius influences the preferred insertion site.…”

“…130 The sulfur/nitrogen co-doping of carbon nanosheets can accelerate the diffusion of potassium ions, alleviate volume expansion and increase the capacity up to 248 mA h g −1 after 4500 cycles in potassium-ion batteries. 131 It seems that N and S are not bonded together, and the synergistic effect occurs through N–C–S bonds in the hexagonal rings of the graphene sheets. The sodium cell based on S and P co-doped carbon exhibits a remarkable cycling life (3000 cycles), and it was attributed to the adsorption of sodium on the surface of carbon particles.…”

“…From DFT calculations, Li et al found that sulfur/nitrogen co-doping in carbon nanosheets increases their attraction for potassium. 131…”