(Invited) Assessing Impacts of Material Chemistry and Operation Strategies on Capacitive Deionization Energy Consumption and Cost

Tuesday, 3 October 2017: 10:20
Chesapeake 12 (Gaylord National Resort and Convention Center)
S. M. Hand and R. D. Cusick (Civil and Environmental Engineering)
Based on the ability to couple energy storage with ion adsorption, capacitive deionization (CDI) systems have received increased attention as an alternative to reverse osmosis (RO) desalination. Preliminary modeling indicates that CDI must operate at a charge efficiency of 0.8 or greater to compete favorably with RO. In this presentation we will highlight how critical charge efficiency can be reached by incorporating complementary fixed charge groups or faradaic materials into the electrode to enhance both selectivity and capacitance. By replacing commonly employed hydrophobic polyvinylidene fluoride (PVDF) bound electrode ionically charged structural polysaccharides, chitosan (CS) and carboxymethyl cellulose (CMC) as composite electrodes binders, we observed charge efficiency values greater than 0.9 and salt adsorption increased by a factor of three. By incorporating MnO2 onto an aerogel through electroless deposition, we improved charge efficiency to 0.8 while also increasing sodium adsorption capacity by greater than one order of magnitude. These results indicate that model informed design of CDI electrodes could enable cost effective desalination with energy storage materials.