Enhancing High‐Capacity and High‐Rate Sodium‐Ion Storage through Synergistic N,S Dual Doping of Hard Carbon

Abstract

Hard carbon, as the most promising commercial anode materials of sodium‐ion batteries (SIBs), has suffered from the coupling limitations on initial Coulombic efficiency (ICE), capacity, and rate capability. Herein, to break such coupling limitations, sulfur‐rich nitrogen‐doped carbon nanomaterials (S‐NC) were synthesized by a synergistic modification strategy, including structure/morphology regulation and dual heteroatom doping. The small specific surface area of S‐NC is beneficial for inhibiting excessive growth of solid electrolyte interphase (SEI) film and irreversible interfacial reaction. The covalent S can serve as active electrochemical sites by Faradaic reactions and provide extra capacity. Benefit by N, S co‐doping, S‐NC shows large interlayer spacing, high defects, good electronic conductivity, strong ion adsorption performance, and fast Na+ ion transport, which combined with a more significant pore volume result in speedier reaction kinetics. Hence, S‐NC possesses a high reversible specific capacity of 464.7 mAh g−1 at 0.1 A g−1 with a high ICE of 50.7%, excellent rate capability (209.8 mAh g−1 at 10.0 A g−1), and superb long‐cycle capability delivering a capacity of 229.0 mAh g−1 (85% retention) after 1800 cycles at 5.0 A g−1.

Closed pore structure engineering from ultra-micropores with the assistance of polypropylene for boosted sodium ion storage

“…S6 and Table S5 †. Moreover, the calculated D Na + value of the PFCC@PP electrode was 2.09 × 10 −9 cm 2 s −1 , much higher than that of PFC (2.24 × 10 −10 cm 2 s −1 ) and PFCC (6.48 × 10 −11 cm 2 s −1 ) electrodes, 50,51 verifying the faster sodium ion migration kinetics of the PFCC@PP electrode. The convenient charge transfer and ion migration process in the PFCC@PP electrode allowed the superior long-term cycling performance at large current rates, and the capacity could be maintained at 83.6 mA h g −1 at 1 C after 500 cycles with a capacity retention of 78%, as shown in Fig.…”

Ion-catalyzed synthesis of N/O co-doped carbon nanorods with hierarchical pores for high-rate Na-ion storage

“…, B, N, P, S) into the carbon matrix can enlarge its layer spacing, modulate its electron structure, and generate substantial defective/active sites. 12–18 Therefore, sufficient heteroatom doping and reasonable graphitization degree in carbon are keys to promoting electron/charge transportation and thus achieving high-capacity and high-rate Na + ion storage.…”