Abstract
Large lithium-ion batteries (LIBs) demonstrate different performance and lifetime compared to small LIB cells, owing to the size effects generated by the electrical configuration and property imbalance. However, the calculation time for performing life predictions with three-dimensional (3D) cell models is undesirably long. In this paper, a lumped cell model with equivalent resistances (LER cell model) is proposed as a reduced order model of the 3D cell model, which enables accurate and fast life predictions of large LIBs. The developed LER cell model is validated via the comparisons with results of the 3D cell models by simulating a 20-Ah commercial pouch cell (NCM/graphite) and the experimental values. In addition, the LER cell models are applied to different cell types and sizes, such as a 20-Ah cylindrical cell and a 60-Ah pouch cell.
Highlights
lithium-ion batteries (LIBs) are currently used in various systems, owing to their high energy and power density
An LER cell model that efficiently performs accurate calculations was proposed; it can consider the scale-up effects that occur in large LIB cells
We confirmed that the additional internal resistance for the large LIB cells mainly occurs from current collectors by comparing the linear dependency of voltage and current and the equivalent electrical resistance at each DOD
Summary
LIBs are currently used in various systems, owing to their high energy and power density. Since P2D models do not consider the non-uniformity of cell volumes, they are not accurate in predicting the behavior of large-size batteries that have been recently used To overcome these limitations, several studies on multi-dimensional physics-based models that are able to include the actual cell shape in the calculation were proposed. Kim et al [16] set independent model domains for length scales and developed a multi-scale multi-dimensional (MSMD) model framework that calculates the impact of the cell shapes considered in a higher hierarchical model domain and the electrochemical reactions calculated in a lower hierarchical model domain in a coupled manner This enabled first-principle-based calculations on large cells. This study proposes a LER cell model that enables fast calculations while considering the prediction of the behavior of large LIBs regarding the shape of the cell.
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