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A model is proposed and used to parameterize the surface-temperature distribution and electrical response for A123 20 Ah LiFePO4 prismatic cells. The cell interior is described by a porous-electrode charge-transport model based on Newman-Tobias theory, which is coupled to a local heat balance. Simulation output depends on only a few observable dimensionless quantities, allowing parameter estimation via iterative optimization schemes that directly compare computed results with experimental voltage and surface-temperature measurements.Despite the neglect of mass-transport limitations within Newman-Tobias theory, the model accurately predicts the dynamic terminal voltage, as well as the minimum, maximum, and surface-averaged temperature on the cell exterior. The electrochemical and thermal properties extracted from square-wave cycling data with various excitation amplitudes (2 C and 4 C) and short charge/discharge periods (50 s and 100 s) compare well with literature values, showing that it is possible to infer internal material properties by fitting external measurements. The temperature dependence of parameters has clear signatures in the observed voltage.

Using a dynamic optimization method, the optimum charge currents as a function of cycle number during cycling for the lithium-ion cell are obtained. A single particle physics-based model, which includes capacity fade, was applied to simulate the cell performance under low earth-orbit (LEO) cycling conditions. Useful cell life is defined as the number of cycles before the end of discharge voltage drops below 3.0 V or the cell discharge capacity becomes less than 20% of the original discharge capacity. The simulated useful cell life can be increased by ∼29.28% by varying the charge current.

A continuum model of an aprotic lithium/oxygen battery is validated against experimental first-discharge data and used to examine how the apparent cell capacity is affected by macroscopic multicomponent mass transfer, interfacial kinetics, and electronic conduction or tunneling through the discharge product. The model accounts for the three-phase nature of the positive electrode in detail, including an explicit discharge-product layer whose properties and volume distribution generally depend on the local discharge depth. Several hypothetical positive-electrode reaction mechanisms involving different product morphologies and electron-transfer sites are explored within the theoretical framework. To match experimental discharge-voltage vs. capacity and capacity vs. discharge-current trends qualitatively, the discharge-product layer must be assumed to have electronic resistivity several orders of magnitude lower than typical insulators, supporting the notion that the presence of lithium peroxide does not wholly prevent electrons from reaching dissolved reactants. The discharge product also appears to allow charge transport over length scales longer than electron tunneling permits. 'Sudden death' of voltage in lithium/oxygen cells is explained by macroscopic oxygen-diffusion limitations in the positive electrode at high rates, and by pore clogging associated with discharge-product formation at low rates.