Lithium-ion batteries (LIBs) are widely used in portable electronics, electric vehicles and grid storage in these days. During the LIBs manufacturing process, slurry filtration is essential to achieve a homogeneous slurry through the removal of agglomerates. However, it is challenging to prevent undesired agglomerates from breakthrough. The objective of this study was the evaluation of this agglomerates breakthrough during the slurry filtration process. Anode slurry was used since it acts a role of determining battery capacity, life and performance. We also analyzed its rheological properties and evaluated its performances during the filtration. In bead filtration, 370 beads out of 920 were passed through the mesh although bead size was slightly bigger than the pore size of the mesh. It seems that larger agglomerates could be penetrated approximately 40% during the filtration process. The rheological properties of anode slurry were consistent with other research groups which were used for the filtration experiments. Slurry filtration experiments using 80, 100, and 120 single mesh filters indicated that the average number of slurry agglomerates on the mesh filter was approximately 26 EA, with counts of 3, 7, and 16 EA for the 80, 100, and 120 mesh filters, respectively. The average size of the fouling agglomerates for each mesh filter was measured to be 570, 490, and 430 μm larger than the mesh filter pore size. The results of filtration performance indicate that the slurry can handle a maximum of approximately 78,000 L/m² (if agglomerates breakthrough related to the flux decline) or 2,000 L/m² (if agglomerates breakthrough related to the number of deposited agglomerates). In addition, the initial flux of the 20/40/120 mesh filter composition (i.e., highly asymmetric) increased by 3% compared to the conventional composition, and no agglomerates were observed up to 220,000 L/m² at all mesh filters. Based on these research results, it is anticipated that the optimization of the slurry filtration process will contribute to the stable production of LIBs. In order to Since this study was limited to estimating agglomerate breakthrough, further research is needed to evaluate the relationship between agglomerate breakthrough and the number of agglomerates fouling the mesh filter, and also to use fluid dynamic analysis to prevent agglomerate formation.