(136b) Thermodynamics and Chemo-Mechanics of Electrosorption Electrodes for Separation Applications

Integrating renewable energy with desalination technologies is an important challenge, in order to design resilient and decoupled water and energy infrastructures. One integrated technology capable of directly using renewable electrons for salt-based separations is capacitive deionization (CDI). CDI performs ion removal using an electrosorption-based process. Separation is achieved through storing ions within an electric double layer on a high surface area carbon-based electrode. Salt removal is largely related to the physical properties of the electrode material (i.e. surface area, pore size, etc.). Furthermore, the nature of the contaminant (anion, cation, or uncharged species) influences ion packing within the electrode. How species interact and order within the confined region of the electric double layer and the nano and micropores influences the thermodynamic efficiency of separation. This talk examines how chemo-mechanical electrode signatures can be used to describe ion dynamics and separation efficiencies in nonporous carbon and intercalation compounds. Model anionic (phosphate) and cationic systems (alkali ions) are used to systematically evaluate the role of valency and ionic size on separation properties in a wide range of faradaic and electric double layer materials. Separation efficiency is largely influenced by co-ion repulsion dynamics that occur during potential swings (i.e. charge/discharge steps).