The invention relates to an electrode element (1) for an energy storage unit (200), having an electrode body (100) made of an active electrode material (E), wherein the electrode body (100) comprises:- at least one recess (110) on its surface or in its interior,- at least one partial volume (120) of lower density, or,- a cover material (D) that covers a surface area of the electrode body (100), at least section-wise, so that the surface area covered by the cover material (D) remains unwetted when in contact with an electrolyte.The invention furthermore relates to a production method for the electrode element and to an energy storage unit (200) and an implantable electrotherapeutic device.
