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ePaper created 2015-05-08, 15:29:13 | version 1.38.0
CONTINUOUS ELECTROCHEMICAL OPERATION WITH FLOW ELECTRODES Fig. 1: Concept of capacitive deionization (CDI) via fl ow electrodes for facile water treatment. Fig. 2: Concept of the electrochemical fl ow capacitor (EFC) for energy storage. 50 HIGHLIGHTS V. PRESSER, D. WEINGARTH, J. LEE, S. PORADA Ion electrosorption at the interface between electrically charged carbon electrodes and liquid electrolytes is a versatile technology enabling high- ly effi cient energy storage, water desalination, or energy harvesting. While tremendous research activities were spawned by the discovery of novel carbon materials, very litt le variation of the electrode archi- tecture was explored. Energy storage. A major limitation to electrical double-layer capacitors (supercapacitors) is the high cost per unit of stored energy. One approach for large scale systems is to employ fl ow electrodes instead of polymer-bound fi lm electrodes. Flow capacitors provide facile scaling of system metrics: a larger tank with fl ow electrode liquid enables more energy storage and the number and size of charge / discharge cells determines the power performance. Th is way, the amount of housing, current collector, and separator membranes can be signifi cantly reduced. Energy harvesting. Modifying the ion concentration between two fl ow electrode compartments enables the extraction of capacitive mixing energy allowing us to tap, in otherwise, inaccessible energy reservoirs. For example, it enables energy extraction from gradients of salinity or concentration of dissolved CO2. Water treatment. Capacitive deionization is an att ractive technology with the severe drawback of intermitt ent system operation: durations of ion electrosorption are interrupted with mandatory ion release for electrode regeneration. Flow electrodes continuously discharged outside the electrochemical cell enable a continuous operation for highly effi cient water desalination. ENERGY MATERIALS