Time-Sensitivity of Intermediate Product Properties in Lithium-Ion Battery Cell Production

Lithium-ion batteries play an increasingly crucial role in electric vehicles, grid energy storage, and portable devices. In lithium-ion battery manufacturing systems, quality assurance measures are essential throughout the production chain to identify intermediate products that do not meet specifications, ensuring that the finalized cells meet the high-quality standards expected by the customer. This also supports the reduction of the scrap rate and thereby raises the sustainability of production. Parts of the intermediate product properties, particularly evident in electrode production, change over time. Therefore, measurements and tests must be planned accordingly to ensure that decisions regarding the product quality and further processability are accurate. This paper presents a procedure to investigate the time-sensitivity of intermediate product properties and to determine the validity durations for measurement results accordingly. The procedure is experimentally applied to examine the viscosity, density, and solid content of slurries, as well as the coating masses and the spring-back effect of electrodes in an NMC/graphite system.