Comparison of lumped and 1D electrochemical models for prismatic 20Ah LiFePO4 battery sandwiched between minichannel cold-plates

Abstract

In this paper, we present a detailed comparison study on the prediction accuracy by two different and simplified battery models, namely Lumped and Li-ion (1D electrochemical) model, for a prismatic 20Ah LiFePO4 battery sandwiched between minichannel cold-plates with distributed flow. A two-way coupling between the battery model (Li-ion/Lumped) and 3D conjugate heat transfer model is considered for heat generation and dissipation rates at different discharge rates (1-4C) and coolant inlet temperatures (15-35°C). The predicted battery voltage response at room temperature (22°C) and the performance of Battery Thermal Management System (BTMS) in terms of the battery surface temperatures (maximum temperature, Tmax and temperature difference, ΔT) are compared between the models. Further, to get the insights on the battery heating rate by these models, ten different locations are selected on the battery surface and temperature variation during the discharge process are compared. It is found that Lumped model predicted temperatures are in close agreement with that of Li-ion model with a difference of 2.1% at 1C discharge rate. However, the difference has increased to 16.4% at 4C discharge rate, and is attributed to the non-accountability of chemical reactions by the Lumped model in contrast to the Li-ion model (as a benchmark). Therefore, it is suggested to use Lumped model for preliminary studies on designing the BTMS because it requires only three measurable electrical parameters.