Phase field modeling of electrochemically induced fracture in Li-ion battery with large deformation and phase segregation

A finite strain phase field fracture model is presented which treats phase segregation, fracture and the related electrochemical reaction in rechargeable Li-ion battery electrodes in a systematic manner. In particular, a regularized electrochemical reaction model is proposed to account for the reaction on the freshly generated diffusive fracture surface. It is shown that this model is equivalent to the reaction model on a sharp surface. With this regularized formulation, the reaction induced source term is added into the Cahn-Hilliard type evolution equation. Moreover, to ensure that hydrostatic pressure makes no contribution to fracture, a decomposition of the elastic strain energy is proposed. The fracture model is implemented with isogeometric finite element method and used to numerically study the interaction among phase interface, fracture and electrochemical reaction. Simulations show that phase interface can induce crack branching. The electrochemical reaction induced crack formation from micro pores is also observed. Detailed analysis demonstrates that the model takes reasonably into account phase segregation, fracture, electrochemical reaction, and especially their interplay