Process modeling of the electrode calendering of lithium-ion batteries regarding variation of cathode active materials and mass loadings

The process chain for production of lithium-ion battery electrodes commonly includes the compaction by calendering. This process step decisively determines the pore structure of the coating and therefore the electrochemical performance of the produced lithium-ion battery cells. For the targeted adjustment of the pore structure, it is of substantial interest to be able to control this process comprehensively. In this study, a Heckel-based model equation is supplemented by a predictive model for the lowest achievable coating porosity based on the theoretical packing structures of equally sized spheres. Using this approach, the influence of different active materials, varying in particle size distribution and mechanical characteristics, on the compaction behavior is examined. An addition of smaller particles as well as increased initial porosities due to coarser particles decrease the compaction resistance. Furthermore, the impact of increasing mass loadings of the coating on the compaction resistance is analysed, resulting in a linear proportional relationship for the considered range from 80 to 280 g/m(2).