A rechargeable battery cell comprises a separator (10) as a load bearing vessel for supporting positive (13+) and negative (13-) electrodes that are attached by embedding and/or by coating or laminating at opposite ends of the separator (10). A carbon structure (12) can be embedded or coated on the separator (10). The carbon structure (12) can be a nano-structure or a carbon nanofiber structure for mechanically strenghtening and stabilizing the separator (10) surface.
