NOVELTY - The method involves forming a film-like casing (4) with a metallic layer (S2) that is arranged between outer and inner plastic layers (S1, S3). An extension of the metallic layer guided-out between the plastic layers is utilized as a reference electrode (6) at which a parameter of a single cell (1) is determined by a voltage measurement and/or a current measurement. A conductivity of the plastic layers is determined as the parameter of the cell by a detected potential difference between the reference electrode and one an electrical pole (2) e.g. negative pole and positive pole, of the cell.    USE - Method for checking quality of a single cell e.g. pouch cell such as lithium ion cell or lithium polymer cell, of a battery of a vehicle e.g. electric vehicle and hybrid vehicle, during manufacturing process.    ADVANTAGE - The method enables utilizing the extension of the metallic layer that is guided-out between the plastic layers, as the reference electrode at which the parameter of single cell is determined by the voltage measurement and/or current measurement such that better checking of the single cell quality can be enabled. The method enables determining damages in form of continuous holes to the inner plastic layer of the casing during manufacture process such that a subsequent failure of the single cell during operation can be prevented, thus increasing working reliability of the single cell while enhancing service life of the single cell. The metallic layer is utilized as a diffusion barrier such that penetration of moisture and/or dirt into interior of the single cell can be prevented.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a device for checking quality of a single cell during manufacturing process.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic enlarged sectional view of a portion of a single cell with a reference electrode.    Outer plastic layer (S1)    Metallic layer (S2)    Inner plastic layer (S3)    Single cell (1)    Electrical pole (2)    Film-like casing (4)    Reference electrode (6)