Abstract: The measurement method according to the invention for an electrochemical energy storage device involves the electrochemical energy storage device being held (S1) and having contact made with it (S2) in a holding device. The electrochemical energy storage device is charged (S3) to a predetermined first charge state. The electrochemical energy storage device is discharged (S4) to a predetermined second charge state. A measuring device is used to capture (S5) at least one measured value for a physical parameter of the electrochemical energy storage device, with the physical parameter allowing the operating state of the electrochemical energy storage device to be inferred.

Abstract: An electrochemical cell comprises at least one negative electrode including at least one material which is capable of absorbing charge carrier; at least one positive electrode including at least one material capable of releasing charge carrier; at least one electrolyte capable of transporting charge carrier, between the electrodes; and at least one protective device that is substantially an integral part in at least one of the electrodes and comprises at least one enclosure, the at least one protective device being designed such that if a damaging influence damaging the electrochemical cell occurs, in particular heat, at least one stabilizing additive is released from inside the enclosure.

Abstract: Electrolyte, comprising an aprotic solvent, a lithium salt as conducting salt, and an additive, characterized in that the additive is a compound which contains a protonable nitrogen atom and is hydrolysable by water.