Abstract: The invention features a flow-through capacitor system that achieves enhanced power efficiency by sequential control and actuation of at least two or more flow-through capacitor cells within the flow-through capacitor system. Alternatively or in addition, power efficiency is enhanced by integrating the purification stages of the system, for example, by placing more than one cell within a single cell casing. Preferably, integrated stage flow-through capacitors are controlled sequentially.

Abstract: Flow-through capacitors are provided with one or more charge barrier layers. Ions trapped in the pore volume of flow-through capacitors cause inefficiencies as these ions are expelled during the charge cycle into the purification path. A charge barrier layer holds these pore volume ions to one side of a desired flow stream, thereby increasing the efficiency with which the flow-through capacitor purifies or concentrates ions.

Abstract: The invention features an electrode array (7) in which pairs of electrodes (1) are geometrically arranged so that the broadest faces of the exposed electrodes are not directly opposing to each other. Rather, the broadest facing surfaces of the electrodes in the array are parallel, adjacent, or offset at an angle. The electrode geometry of an electrode array of the invention permits electrodes to be in close proximity, thereby lowering series resistance, while minimizing the possibility for short circuits that can cause electrical leakage. An electrode array of the invention can be used in an electrochemical cell, such as a battery, e.g., a lithium battery, a capacitor, a flow-through capacitor, or a fuel cell.