Single-Particle Model for a Lithium-Ion Cell: Thermal Behavior

15 developed a thermal model for the LiCoO2-mesocarbon microbead MCMB pouch cells based on the PP model and obtained good agreement between model predictions and experimental data. A disadvantage common to the P2D model and the PP model is the long simulation time due to the large number of nonlinear equations, so these models become computationally inefficient for simulating conditions such as cycling behavior and series/parallel configuration of stacked cells in battery packs. To improve computational run time without compromising accuracy, the singleparticle model SP modelRef. 3 and 16 was proposed. The SP model ignores the detailed distribution of local concentration and potential in the solution phase and instead accounts for a lumped solution resistance term. Furthermore, the local reaction currents across the porous electrode are assumed to be constant, which allows treatment of a porous electrode as a large number of single particles, all of which are subjected to the same conditions. These assumptions are reasonable for low applied current densities, thin electrodes, and highly conductive electrodes. In such cases the overpotential is primarily affected by the diffusion in the solid state. At high current densities, the concentration gradients in the electrolyte become important. The model presented here does not include these concentration gradients and is consequently limited to low to moderate current densities. These assumptions simplify the model equations significantly. The SP model using a two term polynomial approximation shows good agreement with the detailed PP model for charge/discharge below 1C, where C denotes the cell capacity. 3 In this work, the single-particle model is extended to include thermal effects by adding the energy balance equation to the SP model. Instead of using a two term polynomial approximation, the solid phase diffusion equations are solved by the eigenfunction expansion method, which improved the accuracy of the model. Parameters in this SP thermal model are estimated by fitting the simulated discharge curves up to 1C rate with the experimental data obtained on lithium-ion pouch cells. Also, good agreement between the SP thermal model and the PP thermal model presented in Ref. 15 is obtained.