Atomistic dynamics investigation of the thermo-mechanical properties and Li diffusion kinetics in ψ-graphene for LIB anode material

A fundamental understanding of the thermo-mechanical properties of the electrode materials and Li-ion diffusion kinetics are indispensable for designing high performance Li-ion batteries (LIBs) with high structural stability and safety. Herein, we performed both molecular dynamics (MD) simulations and density functional theory (DFT) calculations to investigate the thermo-mechanical properties and Li diffusion kinetics in a two-dimensional (2D) defect-filled graphene-like membrane consist of 5-, 6-, and 7-membered rings, called psi (ψ)-graphene. Our results reveal that ψ-graphene has negative linear thermal expansion coefficient, high specific heat capacity, and high elastic constants that satisfy Born's criterion for mechanical stability, which can be elucidated as an evidence of strong anharmonicity in ψ-graphene due to the soft out-of-plane bending modes. These characteristics can help prevent thermal runaway that can occur during overheating and prevent structural damage due to the severe volume expansion of the lithium ion battery (LIB). In addition, a Li diffusion coefficient was estimated to be 10 cm s at 300K with a low Li-ion migration activation energy (