Controlling Structure and Morphology of MoS2 via Sulfur Precursor for Optimized Pseudocapacitive Lithium Intercalation Hosts

Abstract

Molybdenum disulfide (MoS₂)-based electrode materials can exhibit a pseudocapacitive charge storage mechanism induced by nanosized dimension of the crystalline domains, which is why control over material structure via synthesis conditions is of significance. In this study, we investigate how the use of different sulfide precursors, specifically thiourea (TU), thioacetamide (TAA), and L-cysteine (LC), during the hydrothermal synthesis of MoS₂, affects its physicochemical, and consequently, electrochemical properties. The three materials obtained exhibit distinct morphologies, ranging from micron-sized architectures (MoS₂ TU), to nanosized flakes (MoS₂ TAA and LC). While all three synthesized samples exhibit pseudocapacitive Li⁺ intercalation properties, the capacity retention of the latter two consisting of nanosized flakes is further improved at high cycling rates. The individual charge storage properties are analyzed by operando X-ray diffraction, dilatometry, and 3D Bode analysis, revealing a correlation between the morphology, porosity, and the electrochemical intercalation behavior of the obtained electrode materials. The results demonstrate a facile strategy to control MoS₂ structure and related functionality by choice of hydrothermal synthesis precursors.