Ammonium-driven modulation of 1T-MoS2 structure and composite with graphene: A pathway to high-performance lithium-ion battery anodes

The lack of stable anode materials with high capacity and fast redox kinetics has hindered the application of lithium-ion batteries (LIBs) for energy storage. Metal-phase molybdenum disulfide (1T-MoS2) is recognized as a promising energy storage material because of its combination of excellent physical and electrochemical properties. In this paper, we report the insertion of ammonium ions (NH4+) into the MoS2 interlayer and effective complexation with graphene oxide (GO). The MoS2 layer spacing was effectively enlarged from 0.67 nm to 1.1 nm by NH4+ insertion, and this method not only maintains the stability of the 1T phase and reduces the energy barriers for Li+ insertion and de-embedding, but also improves the diffusion kinetics of Li+. The Li+ diffusion coefficients of the prepared 1T-MoS2/G composites were confirmed to be enhanced by three orders of magnitude by constant current intermittent titration technique tests. Compared with the conventional preparation method, the mechanism of action of NH4+ insertion provides a new regulation strategy. In addition, electrochemical studies showed that the specific capacity of the prepared 1T-MoS2/G electrode was 1533 mAh/g for 180 cycles at 0.1 A/g and 1679 mAh/g for 800 cycles at 0.5 A/g. Thus, the strategy of introducing NH4+ intercalation to improve the cycling stability of MoS2 raises the prospect of practical application of layered metal sulfide anodes.