Membrane Capacitive Deionization (MCDI) is a low-cost desalination technology that utilizes ion-exchange polymer coated electrodes to reversibly adsorb and desorb ions. MCDI electrodes are typically prepared using hydrophobic polymer binder and organic solvents. Use of hydrophobic binder negatively affects the wettability of the electrode and use of organic solvent leads to potential health and environmental hazards. Thus, an approach using hydrophilic polymer binder and fully aqueous processing and fabrication route would be desirable. Here, we report a scalable, aqueous processing approach to prepare high capacity ion-exchange polymer coated electrodes for MCDI. Electrodes are first prepared by flow coating an aqueous slurry of activated carbon and a water-soluble polymer binder. After annealing, electrodes are subsequently flow-coated with a thin layer of cation- or anion-exchange polymer. These electrodes exhibit salt adsorption capacities up to 16.7 mg/g and overall charge efficiencies up to 98.6 %, much higher than typically achieved for activated carbon electrodes with hydrophobic polymer binder (5 - 10 mg/g). We attribute the increased capacity and charge efficiency to the use of a hydrophilic polymer binder and ion exchange polymer coating, and our overall approach demonstrates a simple, environmentally friendly, cost-effective and scalable method for the fabrication of high capacity MCDI electrodes.

Aqueous-processed, high-capacity electrodes for membrane capacitive deionization (MCDI)

255th National Meeting (2018)

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