Electrochemical storage device having a state detector

An electrochemical storage device having a state detector, comprising:

• an electrochemical storage device, which has a wall enclosing an electrochemical storage material, wherein the state detector has at least one ultrasound emitter and at least one ultrasound receiver, which are attached on an exterior side of the wall, and wherein the electrochemical storage material is subject to a volume change during operation of the storage device,
• wherein the electrochemical storage material is provided in a liquid form and is in direct contact with the wall during operation of the storage device, and the ultrasound emitter and the ultrasound receiver are attached on the wall such that they are acoustically coupled to the wall,
• wherein the ultrasound emitter is configured to output an emission signal in a direction along the side of the wall, wherein the direction is either towards a top or a bottom of the electrochemical storage device, wherein the ultrasound receiver is configured to receive a response signal and wherein the state detector further includes an analysis circuit configured to analyze the response signal to ascertain a fill level electrochemical storage material in the storage device;
• and wherein the analysis circuit is configured to analyze a first response signal to ascertain a first fill level of the electrochemical storage material and wherein the analysis circuit is further configured to analyze a second response signal different than the first response signal to ascertain a second fill level different than the first fill level of the electrochemical storage material.