Supercapacitors use nanoporous electrodes to store large amounts of charge on their high surface areas, and use the ions in electrolytes to carry charge into the pores. Their high power density makes them a potentially useful complement to batteries. However, ion transport through long, narrow channels still limits power and efficiency in these devices. Proper design can mitigate this. Current collector geometry and electrolyte starvation must also be considered once this is done. Here, De Levie's model for porous electrodes is applied to quantitatively predict device performance and to propose optimal device designs for given specifications. Effects unique to nanoscale pores are considered. Example design outlines for vehicle applications are proposed and compared. The optimal designs are currently not easily accessible given current technology for fabrication of electrodes and separators, but rapid progress in this area has been demonstrated recently [2-4]. Steering fabrication efforts toward these designs should allow for significant performance improvements, expanding opportunities for applications in electric vehicles, portable electronics, and power conditioning in electrical grids with distributed renewable sources.
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