Catalyst layers, unlike traditional barrier coatings, can be considered active coatings because they serve multiple functions related to transport (proton, electron, oxygen). Fundamentally, the distribution of the active and inactive materials in the electrode (or microstructure) is largely dependent on the processing step. Typically, catalyst layers are manufactured using scalable methods such as blade coating, slot-die, or spray coating¹. These methods rely on dispersing the active material in a colloidal ink. Catalyst layer inks are examples of biphasic material systems composed of a solid material, a polymer, and a solvent. Nanoscale interactions between the individual constituents can alter macroscopic properties relevant for coating and manufacturing processes (i.e. viscosity, surface tension, aggregation, and rheology)¹. Control over these macroscale properties is important for controlled electrode formation during scalable roll-to-roll manufacturing. Herein, we study a range of formulated inks composed of different solvents (methanol, isopropyl alcohol, octanol, and water), I:C ratios, and surface charges to build correlations between the feedstock material (inks) and electrode structure (coatings)^2,3. We discuss the trade offs between thermodynamic and physics based modeling of ink-based systems to guide and inform ink design and formulation. Finally, this works focuses on drawing correlations between fundamental inks properties and downstream electrode properties (density, porosity, etc.) derived on a custom-made benchtop slot-die system.

[1] Hatzell, Kelsey B., et al. "Understanding inks for porous-electrode formation." Journal of Materials Chemistry A 5.39 (2017): 20527-20533.

[2] Dixit, Marm B., et al. "Catalyst Layer Ink Interactions That Affect Coatability." Journal of The Electrochemical Society165.5 (2018): F264-F271.

[3] Dixit, Marm, and Kelsey B. Hatzell. "Understanding Binary Interactions and Aging Effects in Catalyst Layer Inks for Controlled Manufacturing." ECS Transactions 80.8 (2017): 301-307.