A Generalized 3D Multiphysics Model for Li-Ion Intercalation Batteries

We present the computational implementation and results of a unified formulation across the electrode-electrolyte-electrode system. This formulation utilizes a rigorous volume averaging approach typical of multiphase formulation 1, 2 and recently extended to supercapacitors 3 . Unlike previously used methods for Lithium ion batteries based on a segregated formulation 4, 5 with intermediate boundaries, by having a unified, single-domain approach, complex geometries are naturally incorporated with the numerical algorithms guaranteeing stability and convergence. The same formulation also applies to 1D, 2D and 3D geometries irrespective of the complexities associated with dimensionality as well as with electrode/electrolyte spatial arrangements. In addition, the formulation accounts for any spatio-temporal variation of the different properties such as electrode/void volume fractions and anisotropic conductivities. This generality will aid in upscaling of local material properties directly into the system-level model. The resulting governing equations are solved using finite element techniques. The modeling results are validated for standard Li-ion cells and compared against the cell level performance (see Fig. 1 for sample results). Furthermore, we conduct an investigation of the effect of spatial variability of the void volume fraction and anisotropy on the performance of multidimensional cell configurations. We analyze the cell level performance and relate it to the detailed spatio-temporal variations of charge and discharge behavior in the electrodes. Finally, we present the coupling of the electrochemical, electrical, thermal, and mechanical processes inherent to cell performance. References: 1. A. Prosperetti, in Computational Methods for Multiphase Flow , edited by A. Prosperetti and G. Tryggvason (Cambridge University Press, Cambridge, 2007). 2. C. Y. Wang, W. B. Gu and B. Y. Liaw, J. Electrochem. Soc. 145 (10), 3407-3417 (1998). 3. S. Allu, B. Velamur Asokan, W. A. Shelton, B. Philip and S. Pannala, Journal of Power Sources 256 (0), 369-382 (2014). 4. P. Arora, M. Doyle and R. E. White, J. Electrochem. Soc. 146 (10), 3543-3553 (1999). 5. M. Doyle, T. F. Fuller and J. Newman, J. Electrochem. Soc. 140 (6), 1526-1533 (1993).