Controllable synthesis of tunable few-layered MoS2 chemically bonding with in situ conversion nitrogen-doped carbon for ultrafast reversible sodium and potassium storage

Abstract

Tunable few-layered MoS 2 chemically bonding with in situ conversion nitrogen-doped carbon are synthesized for ultrafast reversible sodium and potassium storage. • A controllable and simple strategy to fabricate MoS 2 /SNC. • Strong C-S bond provides stable structure support. • The effect of layer number on electrochemical performance are systematically studied in depth. • Super cycling stability and high rate capability were achieved for SIBs and KIBs. MoS 2 with a special two-dimensional layered structure has attracted extensive interest as anode materials for sodium-ion batteries (SIBs) and potassium-ion batteries (KIBs) because of the large interlayer spaces (ca. 0.62 nm) enabling facile Na + /K + intercalation. However, the application of MoS 2 in SIBs and KIBs is impeded by poor cycling stability and low rate capability, which are associated with the instability of the electrode architecture and the sluggish transfer/diffusion kinetics of charge/ions. Here, a controllable and simple strategy is realised by tunable few-layered (2–4 layers) MoS 2 chemically bonding (C-S) with in situ conversion nitrogen-doped carbon. Serving as a universal anode materials for SIBs and KIBs, the electrode delivers unprecedented rate capability and long cycle life. The few and expanded layers tightly chemically bonding with nitrogen-doped carbon not only shorten the Na + /K + diffusion length, expose the more active site and reveal smaller energy barriers but also prevent the volume strain induced by the Na + /K + intercalation. The sodium and potassium storage behavior is explained through studying the phase change of storage process and kinetics analysis that a high ratio of capacitive-energy-storage (92% and 84% at 1.0 mV s −1 for SIBs and KIBs, respectively) is dominated especially when at a high rate.