A package for an electrochemical double layer capacitor comprises a housing defining an interior volume, the housing having an end wall, side walls, and an end cap configured to sealably engage with the side walls to enclose the interior volume, wherein the interior volume has a height (hcan) and a diameter (dcan) such that an aspect ratio defined as hcan/dcan is in a range of 3.1 to 15. An electrode set adapted to be incorporated into the package can have an aspect ratio in a range of 3.1 to 15.