Hybrid materials consisting of nanosized molybdenum disulfide (MoS2) and advanced graphene are synthesized hydrothermally using ammonium tetrathiomolybdate and thermally reduced graphene oxide. The drying procedure of the samples - in the air or in a freeze dryer followed by annealing - is found to affect the particle size of the material. Electron microscopy reveals an increase in the lateral size of MoS2 nanoparticles formed on the surfaces of graphene sheets and a higher dispersion of these sheets when the second method of post-synthetic treatment is used. Both hybrid materials demonstrate stable performance as anodes for lithium and sodium ion batteries at room temperature and at –20 °C. The material dried in the air has the highest specific capacities in the entire temperature range, which is explained by a large number of structure defects in MoS2 crystallites and the effective interaction of metal ions with the carbon component. The advantage of the hybrid material obtained by the freeze drying and annealing consists in a smaller loss of the sodium-ion battery capacity when the temperature decreases.
Zaguzina et al. (Sun,) studied this question.