Slot die head is the most critical part for roll-to-roll slot die coater. The performance of the slot die head depends on how it distributes the slurry from a single point (the inlet) to a wide, uniform line (the exit). (1) Manifold: It is the internal cavity (usually coat-hanger or T-shaped) designed to ensure that the fluid pressure is identical across the entire width of the die. For battery slurries, a coat-hanger manifold is preferred because it prevents "dead zones" where NMP-based slurry could stagnate and dry out. (2) Die Lips: The "lips" are the final exit point. They must be polished to a mirror finish (typically Ra < 0.0 um) and have a "sharpness" radius of less than 10 um. This sharpness is what allows the liquid "bead" to break cleanly when doing intermittent (patch) coating.

References:

F. Sarka, et al., Design Issues for Slot-Die Coating Heads - Case Study, IOP Conf. Ser.: Mater. Sci. Eng. 2022, 1237, 012014

X. Ding, et al., A review of the operating limits in slot die coating processes, AICHE J, 2016, 62, 2508-2524

A. Hoffmann, et al., Optimized battery electrodes with primer layers by simultaneous two-layer slot-die coating, The European Physical Journal Special Topics, 2025, 234, 3065–3076.