First-Principles Study of Lithium Borocarbide as a Cathode Material for Rechargeable Li ion Batteries

Abstract

Computational simulations within density functional theory are performed to investigate the potential application of a lithium borocarbide (LiBC) compound as a unique material for lithium ion batteries. The graphene-like BC sheets are predicted to be Li(+) intercalation hosts with the Li ion capacity surprisingly surpassing that of graphite. Here, the layered LixBC structure is preserved with x ≥ 0.5, indicating that half of the Li ions in the LiBC compound are rechargeable. Furthermore, the intercalation potential (equilibrium lithium-insertion voltage of 2.3-2.4 V relative to lithium metal) is significantly higher than that in graphite, allowing Li0.5BC to function as a cathode material. The reversible electrochemical reaction, LiBC ⇌ Li0.5BC + 0.5Li, enables a specific energy density of 1088 W h/kg and a volumetric energy density of 2463 W h/L. The volume change is less than 3% during the charging and discharging process. This discovery could lead to the development of a unique high-capacity LiBC Li ion cathode material.

Keywords: Li ion battery; boron; cathode; charge transfer; electron deficiency; energy storage; graphitic materials.