Comparison between computer simulations and experimental data for high-rate discharges of plastic lithium-ion batteries

Computer simulations are compared with experimental data for Bellcore PLION (R) cells using the graphite/1 M LiPF6 in EC:DMC (2:1)/LiMn2O4 system. The motivation is to model lithium-ion polymer cells having higher active mater ial loadings and competitive energy densities and specific energies to liqu id lithium-ion batteries. Cells with different electrode thickness, initial salt concentrations, and higher active material loadings were examined usi ng the mathematical model to understand better the transport processes in t he plasticized polymer electrolyte system. A better description of the ioni c conductivity is employed based on new conductivity data. Improvements in the agreement between the simulations and experimental data are obtained by using the contact resistance at the current collector/elec trode interface as an adjustable parameter for different cells, whose value s vary from 20 to 35 Omega cm(2) (based on separator area). The contact res istance is believed to originate at the mesh current collector interfaces. Reducing the salt diffusion coefficient by a factor of two or more at the h igher discharge rates was necessary to obtain better agreement with the exp erimental data. Based on the experimental data and model predictions from t his study, it can be concluded that the solution-phase diffusion limitation s are the major limiting factor during high-rate discharges. (C) 2000 Elsev ier Science S.A. All rights reserved.