A Numerical Study of the Effects of Cell Formats on the Cycle Life of Lithium Ion Batteries

The effect of cell format on the imbalance and degradation of Lithium Ion Batteries is investigated using a three-dimensional model that solves thermal-electrical-electrochemical-coupled physics. A pouch cell, a cylindrical cell and a prismatic cell are modeled to have the same capacity, the same volume and the same electrode design. Highly nonuniform behavior is observed in the cylindrical cell due to large electrical resistances in the current collectors and to poor heat transport in the radial direction. Degradation of the cylindrical cell is also the fastest among the three cells due to the elevation of its cell temperature by the high joule heat generation and small surface area. The prismatic cell shows the least imbalanced response, and the pouch cell takes advantage of a large cooling area for degradation. Additionally, the model results for the cells with the continuous tab show that accelerated degradation caused by the cell design can be considerably mitigated by improving the electrical configuration.