Doping at sp³-site in Me-graphene (C568) for new anodes in rechargeable Li-ion battery

In this theoretical study, the monolayer carbon allotrope, Me-graphene (also called C568), was respectively doped with Al, Si, P, and Ge atoms by substituting the sp³-hybridized carbon atom in its unit cell to manipulate its physical properties. Theoretical calculations based on the density functional theory (DFT) confirmed the dynamic stabilities of the related doping systems. Interestingly, the mechanical strengths of the doping systems are even stronger than the pristine one. After doping with Si atom, the band gap of the Me-graphene system narrowed from 1.097 eV to 0.987 eV estimated at HSE06 level. However, the Ge-dopant at the sp³-site has very limited influence on the band gap. In the other two cases with Al and P dopants, the systems changed to be metallic because their Fermi levels cut into the valence bands to a certain extent. Additionally, the adsorption sites of Li atoms and the energy profiles of the Li migrations on the related 2D material systems were also investigated in order to reveal their application potentials as anodes in lithium-ion batteries (LIBs).