Chlor-alkali (CA) membranes as key materials to generate chlorine gas and sodium hydroxide are composed of sulfonic acid layer (S-layer) and carboxylic acid layer (C-layer) to provide fast sodium ion transport and slow hydroxide ion diffusion, respectively. Aciplex F, a representative CA membrane is made in a double layer form via thermal adhesion of both layers after each single layer film is independently fabricated. Unfortunately, the membrane fabrication induces delamination particularly in their interface as a result of hydroxide ion diffusion occurring during CA operation, leading to rapid increase in electrochemical overpotential. In this study, selective chemical conversion technique was developed to solve the delamination issue. Their effectiveness was proved by applying the same concept to a wide range of PFSA membrane.

Anion exchange membrane (AEM) with fixed charged cationic groups can selectively transport anionic molecules such as hydroxide anions. The AEM materials have been widely used in the wide range of applications such as polymer electrolyte fuel cells, water electrolysis, and reverse electrodialysis and electrodialysis. Commercially available AEM materials show high electrochemical resistance owing to their chemical architectural features leading to less separated hydrocarbon morphologies. Very low solubility to casting solvents and weak chemical durability to alkaline atmosphere of the AEM materials also makes it difficult to make thin and tough AEM membranes. In this study, AEM materials composed of perfluorinated architectures with improved chemical durability and intrinsically well separated morphologies were developed and evaluated.

Saline water electrolysis (SWE) is an electrochemical technology to directly generate valued chemicals such as chlorine gas (Cl2), hydrogen (H2), and sodium hydroxide (NaOH) by applying electric energy. The key materials in SWE are cation exchange membranes with high selectivity to sodium ions under chemically harsh SWE conditions. The representative SWE membranes are perfluorinated double layered membranes composed of perfluorinated sulfonic acid layer and carboxylic acid layer to transport sodium ions rapidly and to prevent the passage of hydroxide ions, respectively. The commercially available membranes are, however, suffering from delamination issues occurring in their interface. In this presentation, delamination-free membrane fabrication processes will be addressed.

The anion exchange membrane (AEM) has a structure having a group of positively charged ions inside, and selectively permeates the anion of the electrolyte. In addition, excellent ion conductivity and chemical durability, and highly reliable electrochemical performance are required. However, commercially available AEMs have a hydrocarbon-based backbone. It is difficult to make the thin film because of low solubility. As a result, it has low ionic conductivity and high area resistivity and shows limitations in electrochemical applications. In this study, a perfluorinated ionomer-based anion exchange membrane with excellent chemical stability is prepared and shows enhanced anion conductivity in electrochemical applications.