Integrated electrode-membrane assemblies for energy efficient MCDI across the salinity spectrum

This project seeks to advance membrane capacitive deionization (MCDI) technology for purifying feed water streams of varying salinit,y concentration. MCDI is a scalable, energy efficient, and portable water desalination platform that is suitable for U.S. Navy and M,arine Corps missions in expeditionary environments. The standard desalination technology, reverse osmosis membranes, requires larger, systems, high pressure operation, and technical maintenance of filters and parts, making squad-level operations challenging. MCDI a,ddresses these challenges but is currently limited to brackish water desalination due to the low adsorption capacity of the electrod,es and high internal device resistances associated with membrane-electrode interfaces. This project seeks to overcome these current,limitations by developing high-capacity Faradaic electrodes and engineering the membrane-electrode interface. The overall goal of th,e project is to establish structure-property relationships between membrane-electrode interfacial area and fabrication method to int,erfacial ionic charge transport and charge-transfer resistances and their subsequent impact on MCDI deionization performance and ene,rgy consumption (e.g., average salt adsorption rate (ASAR) and energy normalized adsorbed salt (ENAS)). Membrane electrode assemblie,s (MEAs) with large interfacial areas will be attained through advanced surface patterning of ion-exchange membranes. High-capacity,Faradaic electrodes will be deposited on to the membrane surfaces using state-of-the-art MEA fabrication techniques. Additionally, t,he project investigates MCDI stability during seawater deionization. Potential failure modes and mechanisms will be identified throu,gh post-mortem analysis of MEA components using advanced metrology. Uncovering the degradation phenomena is vital for devising mitig,ation strategies.The anticipated outcomes of the project include: (1) identified relationships between membrane patterning and MEA f,abrication method and their influence on charge transfer and interfacial resistances in MCDI systems and MCDI performance when treat,ing water of varying salinity; (2) Faradaic anode and cathode materials for efficient seawater desalination using MCDI; and (3) iden,tification and mitigation of failure modes during MCDI seawater desalination. Accomplishing these technical outcomes will accelerate, the technical readiness level (TRL) of MCDI making it an agile and robust desalination planform for achieving water security during, U.S. Navy and Marine squad-level missions.Approved for Public Release