The complex structure and performance of lithium-ion batteries (cells) are substantially influenced by their manufacturing processes, especially the drying of electrode films. The insights provided by Nikpour et al. (2022), through their thorough analysis of how drying temperatures affect electrode microstructures and, subsequently, battery functionalities, are valuable references for designing the manufacturing processes of lithium-ion batteries.
The selection of drying temperature of active material formulations significantly impacts the performance of the battery. Drying them in a specific temperature range of 24°C to 232°C induced notable variations in their microstructural characteristics.
Rising drying temperatures fundamentally alter the electrode’s microstructure. At the microscopic level, a shift in drying temperature causes a tangible migration of 'binder material' within the electrode. The pattern and extent of this migration reveal that the drying process is more than a simple removal of moisture. It is reshaping of internal architectures too.
Electronic conductivity of the electrode, essential for efficient battery operation, is dependent on drying temperature. Notably, 80°C emerges as an optimal drying temperature for the test electrodes (NMC), maximizing conductivity. However, post-calendering (a compaction process), the differences in conductivity based on drying temperatures seem to narrow.
Higher drying temperatures might save time but at a cost. As temperatures increases beyond 80°C, the contact resistance in both anodes and cathodes increases. The migration of the binder, away from crucial contact points, is a prime suspect behind this increasing resistance.
The movement of ions, crucial for battery operation, is hampered as drying temperatures rise. This phenomenon, reflected in increased ionic resistance, seems rooted in binder and carbon migration, which establishes obstacles for ion movement.