MoS2—Carbon Materials Composite with Dual Phase of MoS2 and Their Application for Anode of Lithium Ion Battery

Abstract

Carbon materials such as graphite, graphene, and CNT are mainly used as anode materials for LIBs because of their wide surface area and excellent stability in Lithium Ion Battery operation. However, graphite, which is mainly used as an anode material, has a very low theoretical capacity of 372 mAh/g. As high-capacity LIBs are increasingly needed like electric vehicles, many studies are being conducted to increase LIB capacity. For example, research on Si anode materials is attracting attention, and Si has a high theoretical capacity of ~4200 mAh/g. However, since there is a fatal disadvantage of volume expansion in cycle performance, stability can be a major defect in the driving condition of LIB.Transition Metal Dichalgogenides (TMD) materials are attraction a lot of attention as various energy materials such as HER and ORR as well as LIB. Their structural characteristics, low price, and high capacity in terms of energy storage make them very attractive to study as a new anode material for LIB batteries. MoS2 belonging to the TMD material is known to have a theoretical capacity of 670 mAh/g. In particular, MoS2 has a single layer structure, and this single layer structure is coupled by weak van der walls force. These properties are very advantageous for exfoliating MoS2 to form a layer-by-layer form with other materials. MoS2 is known to have a typical 1T, 2H structure. However, MoS2, which exists in a stable phase, generally has a 2H structure and has semiconducting properties. Therefore, it is less conductive than graphene, which can be an obstacle to being used as an anode. MoS2 is known to have a typical 1T, 2H structure. However, MoS2, which exists in a stable phase, generally has a 2H structure and has semiconducting properties. Therefore, it is less conductive than graphene, which can be an obstacle to being used as an anode. 1T structure is known to have very good conductivity because it has conductive properties. Therefore, when used as an anode, it has many advantages in that it has conductivity, but since it is a metastable structure, it can be converted to 2H very easily, so it is not easy to maintain the structure.In this study, the synthesis of MoS2 and graphene composites was performed in one pot using a chemical exfoliation method. In addition, it was possible to stably maintain the metastable 1T structure of MoS2 by using graphene as a support material through a post-treatment process in this process. The diffusion of Li+ was promoted by having a 1T structure with a wide interfacial spacing and high conductivity, and superior conductivity and high capacity were stably maintained compared to a composite having a 2H single phase. Through this, a stable and high-capacity anode material was realized using the high energy storage capacity of MoS2 and the stability of graphene.