Lithium-ion batteries modeling: A simple fractional differentiation based model and its associated parameters estimation method

This paper deals with lithium-ion batteries modeling. From an electrochemical model available in the literature, several assumptions and simplifying hypotheses are proposed in order to get a simpler but accurate model. The obtained model is based on a fractional transfer function resulting in the resolution of a partial differential equation that describes the lithium ion diffusion inside the electrodes. The model involves only three parameters and a polynomial that fits the open circuit voltage of the battery. A method to estimate the model parameters and the polynomial is proposed. A single discharge test (constituted of several discharge steps) is required to operate the parameter estimation method. The accuracy for battery voltage prediction of the resulting model is evaluated with various tests.