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Comparison of Modeling Predictions with Experimental Data from Plastic Lithium Ion Cells
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1996
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EngineeringModeling PredictionsExperimental DataDiffusion CoefficientModeling And SimulationPulse PowerMaterials ScienceElectrical EngineeringBattery Electrode MaterialsLithium-ion BatteryLithium-ion BatteriesEnergy StorageSolid-state BatteryElectrochemistryElectric BatteryLithium‐ion BatteryLi-ion Battery MaterialsModest Diffusion LimitationsBattery ConfigurationElectrochemical Energy StorageBatteriesAnode Materials
The study explores different system designs using a mathematical model to achieve higher specific energy. The model incorporates additional internal resistance via contact or film resistance and modest diffusion limitations in the carbon electrode to fit lithium diffusion coefficients, guiding design of higher‑specific‑energy systems. Modeling shows good agreement with experiment, revealing the battery is ohmically limited, with diffusion limitations in the carbon electrode and solution‑phase diffusion at high rates, yielding low‑rate specific energy of 70–90 Wh/kg and peak power dropping from ~360 W/kg to ~100 W/kg, while optimized 6‑h discharge designs can exceed 100 Wh/kg.
Modeling results for a lithium‐ion battery based on the couple are presented and compared to experimental data. Good agreement between simulation and experiment exists for several different experimental cell configurations on both charge and discharge. Simulations indicate that the battery in its present design is ohmically limited. Additional internal resistance in the cells, beyond that initially predicted by the model, could be described using either a contact resistance between cell layers or a film resistance on the negative electrode particles. Modest diffusion limitations in the carbon electrode arising at moderate discharge rates are used to fit the diffusion coefficient of lithium in the carbon electrode, giving . Cells with a 1 M (mol/dm3) initial salt concentration become solution‐phase diffusion limited at high rates. The low‐rate specific energy calculated for the experimental cells ranges from 70 to 90 Wh/kg, with this mass based on the composite electrodes, electrolyte, separator, and current collectors. The peak specific power for a 30 s current pulse to a 2.8 V cutoff potential is predicted to fall from about 360 W/kg at the beginning of discharge to 100 W/kg at 80% depth of discharge for one particular experimental cell. Different system designs are explored using the mathematical model with the objective of a higher specific energy. Configurations optimized for a 6 h discharge time should obtain over 100 Wh/kg.