Method for checking a battery element stack with regard to the position of battery element layers

A method for checking a stack of multiple battery element layers, each battery element layer comprising:

• of an anode as a first type of electrode, a cathode as a second type of electrode, and a separator, the anode and cathode battery element layers each having a polygonal surface area, and are stacked along a stacking direction that is oriented substantially perpendicularly with respect to the polygonal surface area to make the stack of multiple battery element layers, the method comprising:
• determining, a geometry of the polygonal surface area of at least one of the anodes and the battery element layer in a first determination step;
• stacking the battery element layers in a stacking step to form the stack of multiple battery element layers and subsequently for a position check of at least one of a pair of anode battery layers and/or of a pair of cathodes battery layers stacked in the stack of multiple battery element layers;
• irradiating, in a second determination step, the stack of multiple battery element layers by X-ray radiation that is emitted by an X-ray emitter and detected by an X-ray detector, the X-ray radiation being oriented substantially perpendicularly with respect to the polygonal surface areas of the multiple battery element layers;
• determining, via the detected X-ray radiation, with regard to at least one pair of opposite sides of the stack of multiple battery element layers, the greatest edge spacing that is present between edges of at least one of the pair of anode battery layers and the pair of cathode battery layers;
• checking, in a first check step, whether this greatest edge spacing is less than a first tolerance value, wherein when the greatest edge spacing is not less than the first tolerance value, the stack of multiple battery element layers is assessed as unallowable and when the greatest edge spacing is less than the first tolerance value, a second check step is carried out,
• wherein in the second check step one-half the value by which the greatest edge spacing is less than the first tolerance value is defined as the overhang;
• and
• checking whether the greatest edge spacing is less than a value that results from the sum of the shortest dimension with regard to the determination direction of all electrodes of at least one of the anode battery layers and the cathode battery layers and the difference between a second tolerance value and one-half the overhang, wherein when the greatest edge spacing is not less than the value, the stack of multiple battery element layers is assessed as unallowable and when the greatest edge spacing is less than the value, the stack of multiple battery element layers is assessed as allowable.