NOVELTY - The electrochemical energy store or energy converter comprises: an electrochemically active material in a housing that is made of electrochemically inactive material and a wall of the housing, where a device of the energy store or energy converter is fitted or arranged in, at or on the wall of the housing; and a sealing material (4) at points. A specific volume of the sealing material is increased when a threshold temperature is exceeded. The sealing material is arranged in, at or on the wall of a package.    USE - The electrochemical energy store or energy converter such as a secondary rechargeable electrochemical energy storage cell is useful for a battery, where the secondary electrochemical cells are lithium-ion cells.    ADVANTAGE - The electrochemical energy store or energy converter exhibits improved service life and reliability, high mechanical stability and good sealing performance.    DETAILED DESCRIPTION - The electrochemical energy store or energy converter comprises: an electrochemically active material in a housing that is made of electrochemically inactive material and a wall of the housing, where a device of the energy store or energy converter is fitted or arranged in, at or on the wall of the housing; and a sealing material (4) at points. A specific volume of the sealing material is increased when a threshold temperature is exceeded. The sealing material are arranged in, at or on the wall of a package in such a way that the increase in the specific volume of the sealing material that occurs when the threshold temperature is exceeded, is contribute to sealing off a leak (5) in the package or to close an opening (6) in the device of the energy store or energy converter. The sealing material absorbs heat during the expansion of its specific volume from its surroundings. The sealing material after the completion of the process of increasing its specific volume when a threshold temperature is exceeded, poorly conducts heat and electricity. The sealing material comprises fibers such as a mineral or glass wool, and water before increasing the specific volume of the sealing material when the threshold temperature is exceeded. The sealing material: is disposed as an insert between two layers of package consisting of layers or housing; is partially arranged outside of a battery housing; and is arranged so that it prevents or hinders the occurrence of arcs or sparks in the area on a housing surface or an electrical conductor of the electrochemical energy store or energy converter.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of an electrochemical energy store or energy converter.    Sealing material (4)    Leak (5)    Opening. (6)