One example includes a plurality of substantially planar electrodes disposed in a stack, in alignment, the stack being at least partially disk-shaped with a first major face opposing a second major face, with an edge extending between the first major face and the second major face, a pocket, with a covered portion of the stack disposed in the pocket, the pocket shaped to conform to the stack with a first portion of the pocket covering a first segment of the first major face, a second portion covering a second segment of the second major face opposite the first segment, and an edge portion covering the edge of the stack, wherein a remaining portion of the stack extends out of the pocket and a film disposed over the remaining portion of the stack, substantially covering the remaining portion.