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

Abstract MoS2 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 MoS2 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) MoS2 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.