Abstract: A method of determining a state or a state change of an electrochemical energy storage device that includes a housing composed of a multilayer composite film, wherein the housing includes a first housing part and a second housing part composed of the multilayer composite film, which parts are joined to one another, and together enclose a hollow space in which the composite is arranged, and the composite film includes a ply composed of a metal layer and also two plies composed of polymer, with the metal layer being arranged between the two polymer plies, wherein to determine the state or the state change, an electric potential is applied to the metal layers of the first housing part and the second housing part so that an electric field arises between the metal layers and an electrical parameter influenced by a change of a spacing between the metal layers is determined.

Abstract: A method of determining a state or a state change of an electrochemical energy storage device that includes a housing composed of a multilayer composite film, wherein the housing includes a first housing part and a second housing part composed of the multilayer composite film, which parts are joined to one another, and together enclose a hollow space in which the composite is arranged, and the composite film includes a ply composed of a metal layer and also two plies composed of polymer, with the metal layer being arranged between the two polymer plies, wherein to determine the state or the state change, an electric potential is applied to the metal layers of the first housing part and the second housing part so that an electric field arises between the metal layers and an electrical parameter influenced by a change of a spacing between the metal layers is determined.