Interaction and Diffusion of Li and Li+ with Defective Graphene A comparative DFT study

Graphene is a substance with notable properties and uncommon thermal, optical and mechanical characteristics. The very high specific surface of graphene makes this material as an ideal support for catalysts and gas sensors [1]. It is a single layer of carbon atoms that arranged in aromatic rings, forming a honeycomb like structure. Graphene is a semimetal [2], a densely packed two-dimensional (2D) sheet of sp2-hybridized carbon system, owing to its special structural and notable properties [3-7] has become important in the field of material science and has numerous potential applications [8−9] .We investigated the defected graphene for diffusion Li and Li+.in this defected central C6 was removed and one crown of C6 unit saturated with 6H atoms were used. The resulting structure can be described to that of the molecule without its central C6 atoms is C90 H30. The properties and reaction these cases on graphene quantum dot sheet were studied by means of first principles based on density functional theory. We analyzed the thermodynamic and structural properties of this defected graphene, and compared interaction between single Li and Li+ and this defect. Finally diffusion and scanning of these cases were performed. All DFT calculations performed using Gaussian 09 package at the M062X/6-31G* computational level of theory. The diffusion barrier values, show the advantage of doped graphene for use in LiBs with respect to pure graphene. Examples of applications of these defects include supercapacitors, batteries, sensors, fuel cells, solar cells, and photocatalyst.