Modelling of calendering process in Li-ion batteries via continuum-discrete approach

  • Galvis, Andres (University of Portsmouth)
  • Foster, Jamie (University of Portsmouth)

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A novel model to reproduce the caledering process performed on electrodes as part of the manufacture of Li-ion batteries (LiB) is proposed, where electrodes based on Li[Ni1/3 Mn1/3 Co1/3]O2 (NMC) cathodes are analysed. It strongly affects the microstructure of the electrodes and the performance and life of the LiB [1]. The mathematical approach comprises the macroscale where this industrial procedure is applied regarding the heterogeneities of the microscale and its constituents. At the microscopic level, the electrode is composed of visco-elastic porous polyvinylidene fluoride (PVDF) with typical pore size O(10−7 m) as a binder matrix, that contains within its domain (90%-wt.) of NMC active particles. Then, the electrode is coated on an aluminum substrate and subsequently dried (pore pressure p=0 MPa) with a double-site configuration where the current collector thickness is approximately 23.5 µm. Due to the small time scale of this process O(10−1 s), the effects of the relaxation of the viscoelastic PVDF is negligible [2]. Therefore, this is a computational model formulated from the coupling of the continuum equations for elasticity and the coulomb friction model, which can be linked from the assumption that the NMC particles are considered perfectly rigid compared to the surrounding PDVF binder matrix by the order of O(10−2 s). The compactation of the electrode is carried out mainly following part of the configuration described in [1] and the references therein. Results show how the electrode suffers the compactation driven by two steel alloy rollers of 215 mm in radius and how it experiences elastic recovery. REFERENCES [1] Gimenez C. S., Finke B., Schilde C., Frobose L., and Kwade A. Numerical simulation of the behavior of lithium-ion battery electrodes during the calendaring process via the discrete element method, Powder technology, 349:1-11, 2019. [2] Foster J. M., Huang X., Jiang M., Chapman S. J., Protas B., and Richardson G. Causes of binder damage in porous battery electrodes and strategies to prevent it, Journal of PowerSources, 350:140151, 2017.