Insights into cathode densification of calendering process by the combination of in-situ CT and DEM

The calendering process, which is a common compaction technique, serves as the final step in the manufacturing of lithium-ion battery electrodes. Calendering plays an irreplaceable role in enhancing the volumetric energy density and electrochemical performance due to the densification of pore structure. To investigate the densification of active particles, this study designs and develops a micro-CT loading device, which can capture the in-situ evolution during the electrode compression. By combining the in-situ CT with discrete element method (DEM) scheme, we analyze the internal load transfer paths, particle contacts, and pore structure evolution during the densification. The results indicate that the particle compaction process can be divided into two stages, exhibiting a state transition from a non-uniform compaction stage to a uniform compaction stage, and the large particles show a higher breakage risk after over-compaction. This study successfully in-situ tracks the densification during electrode compression and it would promote a deeper understanding of the evolution of electrode microstructure and particle fracture, and optimize the structures and performance of electrodes.