Testing and Modeling the Mechanical Properties of the Granular Materials of Graphite Anode

The graphite anode of commercial lithium-ion batteries is a typical granular material embedded in a soft binder. To investigate its mechanical properties, a combined experimental/theoretical/numerical study is proposed and performed. On the experimental side, a systematic procedure is established, including graphite anode slurry preparation, cylindrical sample manufacturing, axial/lateral compression tests of the sample, and data analysis. On the theoretical side, the Drucker-Prager cap model, which has been widely used in the powder industry, is adopted. The inter-particle portion of the yields surface of the model is calibrated using the experimental results. On the numerical side, a model in Abaqus/explicit is established with the discrete element method. The Young's modulus of particles and the surface energy per unit area are identified as the two dominant factors that control the contact property of the particles in the discrete element method simulation. By adjusting the two factors together with iterations, a set of optimal values are determined so as to render satisfactory simulation result that can predict the deformation pattern as well as the strength of the granular anode material. At last, the deformation mechanisms of the material are discussed based on the experimental and numerical results.