First Principles Study of the Role of Defects for Graphene Lithiation
Note that earlier experimental studies have identified the existence of defects such as Stone-Wales and double vacancy defects, as well as grain boundaries in graphene. Thus, for complete understanding of the electrochemical performance of graphene, the role of different types of defects on the electrochemical performance should be identified as well as the defect density influence should be evaluated. Such comparative study along with pristine graphene can provide vast amount of information not only for the electrochemical performance, but also, for the structural and electronic structure differences with the types of defects, defect densities, and Li concentration.
In this study, we use density functional theory to build atomistic level understanding of topological defects in graphene and their role on the electrochemical performance. Li configurations are generated combining an algorithm whose results are tested using a genetic algorithm method. We explore the effect of each defect type on Li adsorption and obtain an atomic level understanding of the interaction between defected graphene and Li. The electrochemical performance of these defective sheets under varying Li concentration is studied, and compared with those obtained for pristine graphene. Furthermore, the effect of defect density on the electrochemical performance is evaluated. Lithiation voltages as function of each defect type will be reported and compared with those of the pristine graphene. The results are expected to shed light on the role of each defect type on the electrochemical performance of graphene as an alternative anode material for Li ion batteries.