An electrode for electrolytic capacitors having a large capacitance and having excellent tan \u03b4, heat resistance, humidity resistance and stability. The compounds of the present invention having the following formula, wherein R1, R2, R3, R4, R5 and R6 represent, independently, hydrogen, alkyl, aryl, alkaryl, aralkyl, cycloalkyl, heterocycloalkyl, or alkenyl groups; R7 represents hydrogen, alkyl, aryl, alkaryl, aralkyl, cycloalkyl, alkenyl groups, or metals selected from the group consisting of Na, Li, Ca. One web, or both webs, in one pair or in each pair of joined webs has notches in its edge in some of the dents or in the intermediate areas, or both of these, as initiators of deformation.