A new carbon allotrope: Biphenylene as promising anode materials for Li-ion and Li-O2 batteries

Using first-principles computational approaches, we investigate a new carbon allotrope, biphenylene, composed of tetragonal, hexagonal, and octagonal carbon rings as a promising material for Li-ion and LiO2 batteries. We find the Li/C ratio is <1/6 for the single-layer biphenylene which is similar to that of graphene. However, it can reach to lithium composition of Li1C6, Li1C4.5, Li1C4, Li1C3.75, and Li1C3 for bi-, tri-, tetra-, penta-layer, and bulk biphenylene, respectively. It is also found that Li is very mobile on both single-layer and bi-layer biphenylene based on the calculation results of the interaction between Li and substrate and Li diffusion. In addition, we also elucidate the electrochemical performance via the discharge-charge mechanism using Li/biphenylene as electrocatalyst materials of LiO2 battery. Gibbs free energy diagram of the discharge-charge mechanism is illustrated to examine the electrochemical performance. Our results reveal that biphenylene network can be a promising and low-cost catalyst for both Li-ion and LiO2 batteries.