' Atomistic Study of Li Concentration Dependence of the Mechanical Properties of Graphite Anode in Li-ion Battery

The deformation of lithium intercalated graphite anode in Li-ion battery is studied by using molecular dynamics. The quasi-static numerical method is formulated to investigate the mechanical properties of Li-graphite intercalation compounds, LixC6. Under strain-controlling loading, the elastic constants of LixC6 are calculated at 300K. The results reveal that the variation of elasticity tensor components, C-ij, are dependent on lithium concentration. With the increase of lithium concentration, elastic constants C-33 and C-44 rise, whereas the changes in other elasticity tensor components are unconspicuous. The relations of polycrystalline Young's modulus and lithium concentrations are also computed. The calculations adopt three methods including Reuss model, Voigt model and Hill mean-value model. The increment of Young's modulus is larger with the increase of lithium concentration in Reuss model than in other two models. The difference of the calculation results from the diversity of the hypothesis in the models. The result of research are in good agreement with literature data.