Modelling of Large Volume Expansion of Silicon Batteries using an Optimum Incremental Potential Theorem

This paper presents an optimum potential theorem to model the large volume expansion and deformation of Silicon-Mircrowire (Si-MW) anode. Among different silicon anodes, Si-MW is a promising replacement for graphite in lithium-ion batteries (LIBs) leading to high energy density required for electric vehicles (EVs). Nonetheless, charging and discharging of Si-MW result in severe volume expansion and deformation which eventually leads to battery accelerated degradation and capacity fade. A theory is developed to model the phenomenon considering the total free energy and dissipative components. The conservation laws and constitutive relations for Si-MW are connected to the free energy by defining suitable functions. The model equations are discretized and solved using finite-element method (FEM) employing FEAP solver engine. Qualitative sensitivity analysis is conducted on model parameters. The optimum range for the model parameters are extracted which comply with chemomechanical phenomenon in Si-MW.