A cathode subassembly for use in an electrolytic capacitor may include a first separator sheet including a surface having first and second regions, where the second region extends from a perimeter of the first region to a first peripheral edge of the first sheet, a second peripheral edge of a second sheet is substantially aligned with the first peripheral edge, a conductive foil is sandwiched between the first and second sheets and disposed within the first region, the first and second sheets are adhered to each other in a sealing region extending from the second region to a region of a surface of the second sheet facing the second region, and the first sheet includes at least one first recess portion at the first peripheral edge aligned with at least one second recess portion at the second peripheral edge of the second sheet.