Application-oriented modeling and optimization of tailored Li-ion batteries using the concept of Diffusion Limited C-rate

Abstract

To increase the user acceptance and to push electric mobility towards mass suitability, the energy and power density of Li-ion batteries for electric vehicles are among the most crucial features to be improved. The two major approaches to increase the energy density are the development of improved active materials and favorable cell designs. However, the identification of an optimal cell design is a sophisticated challenge due to the large number of interdependent factors influencing the different performance parameters. In the present study, a straightforward model based on the concept of diffusion-limited C-rate is proposed to optimize the energy density of Li-ion battery cells with specified rate performance. The model is introduced and the underlying assumptions are verified by comprehensive experimental investigations. The model is used to identify optimal design parameters of anode and cathode regarding maximum volumetric and gravimetric energy for specified rate performance. A sensitivity analysis is carried out to quantify optimization potentials of cell components and their properties. The results are discussed regarding promising improvement strategies and the practical limits of Li-ion batteries.