Simplification of full homogenized macro-scale model for lithium-ion batteries

Abstract

A simplified model based on the novel full homogenized macro-scale model (FHM) is proposed to reduce the computational time of the FHM model with trivial loss of fidelity. The simplified FHM model is compared with a simplified model based on the pseudo-two-dimensional (P2D) model. The FHM model is based on the homogenization theory, while the volume averaging technique is the basis of the P2D model. Diffusion Partial differential equations (PDEs) are approximated by ordinary differential equations with time-varying coefficients. The intercalation current and conduction equation are also approximated to develop variants of the simplified model. The diffusion and reaction rate parameters of the FHM model are more accurate at high temperatures than the parameters based on the empirical Bruggeman method, as the FHM model parameters are based on the numerical model of the electrode structure. The simulations results verify that, compared with a similar simplified model based on the P2D model, the proposed simplified FHM model is more accurate at 318 K and higher temperature. The output voltage predicted by the proposed simplified model and the simplified P2D model has a root mean square (RMS) tracking error of 0.6% and 2%, respectively, at 1 C input current and 318 K temperature. The computational time of the proposed simplified model is reduced by 35% compared with that of the FHM model, highlighting its superior performance. Discretization of the model is accomplished using orthogonal collocation.