FeS–ZnS Composite Nanosheets for Enhanced Lithium Storage Properties

Ultrathin hybrid nanosheets composed of FeS and ZnS nanocrystals have been synthesized by an organic solution-based synthesis. The formation mechanism of the composite nanosheets is associated with the dodecane thiolatetemplated growth of FeS nanocrystals before undergoing self-assembly into 2D secondary structures. The pre-existing FeS nanocrystals are used as heterogeneous seeds to facilitate the nucleation and growth of ZnS in the vicinity. From the preliminary results, the composite sulfide with a molar ratio of Fe/Zn = 7.29 exhibits specific capacities of 805, 705, 567, 381, and 245 mA h g¹ at current densities of 0.1, 0.5, 1, 2, and 5 Ag¹, respectively, which are higher than electrodes with other ratios and the single component counterparts. Trace amounts of ZnS nanocrystals that are embedded in the FeS matrix bolstered the high capacity resulting from the contribution from ZnS. Meanwhile, this FeS/ZnS nanosheet composite can also sustain a high capacity upon cycling, ascribed to the mutual segregation of the heterogeneous sulfides, in which the co-existence of the heterogeneous sulfides could behave as mutual dispersants to prevent them from aggregating in either lithiation and delithiation processes.