Large area electrolyte coating through surface and interface engineering in roll-to-roll slot-die coating process

We analyzed the dynamics of ink at the liquid–air interface of coating bead, and at the interface between the substrate and wet coated ink in a roll-to-roll slot die coating. Using these studies, stable coating region according to the ink viscosity, flow rate, and coating gap was determined. Mathematical models to predict the geometry of the coated layer according to the flow rate, ink viscosity and contact angle between the substrate and ink were obtained. Using the analysis results, a large area yttrium-stabilized zirconia layer of thickness 15.44 μm and surface roughness 1.13 μm without surface flaws was fabricated, and used as the electrolyte layer in the fabrication of the solid oxide fuel cells. The fabricated cells have the open circuit voltages close to the theoretical values based on Nernst equation in various temperatures, which shows that the YSZ electrolyte was sufficiently dense to gas-tightness.