Modeling Degradation of Battery Materials

The long-term reliability of electrochemical devices is often related to the mechanical integrity of the cathode or anode. In many cases, lithiation or delithiation results in a large change in the lattice parameter of the material. This change in lattice parameter can introduce significant stresses that, in turn, can lead to facture. The fracture process then is a key source of degradation in many battery materials. Devin O’Connor will develop a computational model that couples fracture and the dynamics of the lithiation process. The model will account for a general transformation strain, anisotropic elasticity and the chemical kinetics of charging at the surface of the material. It will be developed within the framework of the phase field method, and will employ finite element methods. This code can thus form the basis of a larger code that can scale well on leadership class machines. The code can be used to model fracture during the lithiation process in materials such as LiFePO4 and LiO2.