Designing Two-Dimensional Graphullerene C36 as High-Performance Anode Materials for Li-Ion Batteries: A First-Principles Study

Two-dimensional (2D) structures hold promise as advanced lithium-ion battery (LIB) anode materials. Recently synthesized 2D graphullerene faces challenges due to its large electronic insulating band gap. In this study, we construct a quasi-tetragonal graphullerene, C₃₆, denoted as GrF-C₃₆, using C₃₆ fullerenes with D_6h symmetry as the structural unit. First-principles calculations revealed that the delocalized p_z orbitals lead to metallicity, combined with intrinsic porosity, resulting in a large theoretical capacity of 496 mAh/g when they are used as LIB anode material. However, the structure exhibits a large migration barrier for lithium ions (Li⁺), limiting its rate performance. To address this, we further adopt the strategy for constructing long-range-ordered carbon by “removing” the [2 + 2] cycloaddition bonds to form intrinsic one-dimensional channels in the structure, denoted as LOPC-C₃₂. Calculations showed that LOPC-C₃₂ maintains metallicity and enhances the structural stability while achieving a Li capacity of 906 mAh/g. The migration barrier for Li⁺ within these channels is only 0.12 eV, significantly improving the rate performance. Coupled with an average open-circuit voltage of 0.43 V and a structural deformation of only 5% at a maximum Li capacity, LOPC-C₃₂ emerges as an excellent anode material. Our work provides a design strategy for the application of graphullerenes in LIBs.