An approximate solution for solid-phase diffusion in a spherical particle in physics-based Li-ion cell models

► In this article, an approximated solution was developed for the solid phase diffusion equation in physics-based Li ion battery model. ► This solution is based on the eigenfunction expansion method, and the truncation error was significantly reduced. ► This approximated solution showed very good accuracy in comparison with numerical solutions such as the FD and OCFE solution. ► The computation time for this approximated solution is greatly reduced because less equations are included.