Energy storage devices, battery cells, and batteries of the present technology may include a housing characterized by a first end and a second end opposite the first end. The housing may include a circumferential indentation proximate the first end. The housing may define a first interior region between the first end and the circumferential indentation, and the housing may define a second interior region between the circumferential indentation and the second end. The batteries may include a set of electrodes located within the housing. The set of electrodes may be positioned within the second interior region of the housing. The batteries may include a cap at least partially contained within the first interior region of the housing. The batteries may also include a first insulator positioned within the housing. The first insulator may extend across the circumferential indentation from the cap to the set of electrodes.