Preparation Of Graphene-SnS₂ Composites And Their Enhanced Lithium Storage Performance

Developing new energy is the most important way to realize the sustainable development of human society. Rechargeable lithium-ion battery, as energy storing device with high energy density, stability, and environmentally friendly properties, is playing very important role in power sources for new energy electric vehicles and various portable electronic devices. The commercial electrode materials of graphite is apparently hard to meet the requirement due to its relatively low capacity and inferior cycle stability. The discovering of graphene brings hope for the breakthroughs of lithium-ion batteries. Especially, lithium-ion batteries based on the use of graphene have recently received increasing attention, and it has been the research orientations for many scientific workers for seeking alternatives of commercial carbon anode materials.Layered tin disulfide(SnS2) are considered as a potential anode material due to its high theoretical specific capacity based on unique conversion or alloying reactions during discharge/charge process. However, its disadvantages, such as low coulombic efficiency, bad electron conductivity and huge volume change, has many severely restricts its widely use as anode materials alone. Considering the above situation, the main research work of this thesis is aimed at improving the lithium storage performance of SnS2 through its modifications by using graphene, and we specifically introduced how to prepare well-defined SnS2/Graphene hybrid structure, then analyzed their synthetic mechanisms. Moreover, we have systematically investigated their lithium storage performances when using the prepared composites as anode materials of lithium ions batteries, and given many detailed analysis of the contribution of the unique composite structure to their enhance lithium storage properties.The full text mainly involves five chapters as summarized as follows:The first chapter is the introduction part, we firstly introduced the research background of this paper and an overview of lithium ion batteries, as well as some situation about the application of SnS2 in anode materials of lithium ions batteries, simultaneously we have also presented some advances in the research of SnS2/Graphene composite materials. Finally, we broadly described our research objectives and significance, as well as the main research contents of this papar.The contents of the second chapter mainly involves the list of chemical reagents and experiment instruments, also the means of investigating the morphologies and electrochemical performance of prepared samples.In the third chapter, we mainly reported a facile two-step method to synthesis SnS2/graphene nanocomposite with the structure of SnS2 nanoplates embedded in the three interconnected graphene network, and detailedly discussed its formation mechanism and the impacts of its microstructure on the electrochemical performance. In addition, we also evaluated the impact of the quantity ratio of the synthesis precursors(SnCl4·5H2O to GO) on their microstructures and electrochemical properties.Three dimensional graphene aerogels have many fascinating properties, in the forth chapters, we introduced a simple and green strategy to obtain SnS2/Graphene hybrid aerogel, and emphatically investigated the condition of reduced graphene oxide and the porosity in the resulting composite, and its further effects on the electrochemical performance of SnS2/Graphene composite when compared with pure SnS2 sample.The fifth chapter is a summary of the full text and outlook for the future. And the last part is acknowledgement.