NOVELTY - The secondary cell (1) has a rechargeable electrode assembly (2) which provides electrical power. A current-conducting unit (3) electrically connected to electrode assembly, is intended to provide electrical energy to consumer from the electrode assembly. A measuring unit (6) detects an operation state of the electrode assembly. A security device (8) reduces the flow cross section of the current-conducting unit, and brings the safe state when the measuring device detects the malfunction condition which deviates from a normal operating state.    USE - Secondary cell for battery e.g. lithium ion battery used for supplying electric energy to motor vehicle (all claimed).    ADVANTAGE - The secondary cell is provided with increased security. The exchange of energy with the electrode assembly of the secondary cell is limited to certain extent, so that the risk potential due to uncontrolled exchange of energy with the electrode assembly of the secondary cell, which extends from the cell served by the secondary circuit, can be reduced. The envelope is dimensionally stable and adapted to provide a stable structure and serve as mechanical mounting for components of secondary cell and/or the fixed arrangement of the secondary cell in higher battery. The components of the secondary battery are protected against environmental influences and against mechanical stress and thermal stress of fluids and/or liquids. No exchange of substances with the environment takes place in normal operation state. The set of values can assume an operating parameter, in order to ensure proper operation of the secondary cell. The measuring device is integrated into the secondary cell so that compact construction and/or maintenance of the secondary cell including cell control unit can be achieved. The safety device comprises a bolt, which is driven by igniting pyrotechnic explosive charge against the current-conducting unit, and reduces the current of current-conducting line cross-section by mechanical unit. The safety device acts on the webs and/or thin points in order to convert the secondary cell to the safety state and to reduce power line cross section.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for method for operating secondary cell.    DESCRIPTION OF DRAWING(S) - The drawings show the schematic views of the secondary cell.    Secondary cell (1)    Electrode assembly (2)    Current-conducting unit (3)    Measuring unit (6)    Security device (8)