one method of manufacturing a polarizable electrode for an electric double - layer capacitor includes , in order , the steps of : preforming a kneaded substance of fine carbon powder , a polymer resin containing fluorine , and a liquid lubricant into a sheet - type preform ; adjusting the content of the liquid lubricant in the sheet - type preform to 10 to 47 percent by weight ; shaping the preform into a prescribed thickness , optionally but advantageously with heated rolls ; and then substantially removing the liquid lubricant from the preform . in another disclosed method , first the liquid lubricant is substantially removed , and then the sheet - type preform is rolled with rollers that are heated to substantially 90 °- 120 ° c . in either of the above methods , the rollers are controlled to have a circumferential speed of 0 . 7 - 5 m / min and the rollers shape the preform into a sheet substantially 0 . 04 to 0 . 5 mm in thickness for serving as a polarizable electrode .