NOVELTY - The electrochemical cell comprises an electrode stack, which is sealed off by a sheath in a gas tight and/or liquid-tight manner, a pressure-relief device (4) in the form of a desired breaking point, where the pressure-relief device has a rupture diaphragm (5), which closes an aperture (6) in the sheath, a thorn (11) or a blade, which breaks parts of the sheath, and a sensor means, which is provided in order to recognize a required pressure relief process. The rupture diaphragm is made of a polymer or a film. The rupture diaphragm and the sheath are made of an identical material.    USE - Electrochemical cell useful in a battery arrangement (claimed).    ADVANTAGE - The electrochemical cell can be produced with improved stability.    DETAILED DESCRIPTION - The electrochemical cell comprises an electrode stack, which is sealed off by a sheath in a gas tight and/or liquid-tight manner, a pressure-relief device (4) in the form of a desired breaking point, where the pressure-relief device has a rupture diaphragm (5), which closes an aperture (6) in the sheath, a thorn (11) or a blade, which breaks parts of the sheath, and a sensor means, which is provided in order to recognize a required pressure relief process. The rupture diaphragm is made of a polymer or a film. The rupture diaphragm and the sheath are made of an identical material. The rupture diaphragm has a diffusion reducing layer and a layer of metal such as aluminum, which is vapor-deposited on the rupture diaphragm. The pressure relief device is designed to introduce a pressure relief process during reaching a burst temperature. The layer of the rupture diaphragm is made of a substance, whose melting temperature lies below the burst temperature. The rupture diaphragm is coated with paraffin. The aperture in the sheath has a round shape or a square shape. The rupture diaphragm is sealed or glued on the aperture and/or is held by means of a holding part on the aperture. The rupture diaphragm has a ground surface that is larger than the aperture of the sheath. A disk- or ring shaped polymer sealing (10) is provided between the rupture diaphragm and the sheath. The pressure relief device is arranged in an area turned away from a current collector of the electrochemical cell or arranged in lower and/or lateral area of the electrochemical cell in the installed condition of the electrochemical cell.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of a sheath of an electrochemical cell.    Pressure-relief device (4)    Rupture diaphragm (5)    Aperture (6)    Sealing disk (10)    Thorn. (11)