Reduction of an electrochemistry-based Li-ion battery health degradation model via constraint linearization and Padé approximation

This paper examines an electrochemistry-based model of health degradation via anode-side resistive film formation in Lithium-ion batteries. The paper makes this model more tractable and conducive to control design by making two main contributions to the literature. First, we adaptively solve the model's algebraic constraints using quasi-linearization. This improves the model's execution speed compared to solving the constraints via optimization. Second, we reduce the model's order by deriving a family of analytic Padé approximations to the model's spherical diffusion equations. The paper carefully compares these Padé approximations to other published methods for reducing spherical diffusion equations. Finally, the paper concludes with simulations of battery degradation that highlight the significant impact of the proposed model reduction approach on the battery model's overall accuracy and simulation speed.