TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The sealing device is disposed in the region of at least one port (5) and/or an electrochemically active region of the terminal bipolar plate. The elements of the sealing device extend to the entire surface or only partially on the end plate and/or terminal bipolar plate. The sealing device is designed such that end plate is not upheld in its entire thickness. The sealing device is made of a single or multilayer coating of the end plate and/or the terminal bipolar plate. The material contains the coating of fluoropolymers, and/or slide-enhancing additives in the form of graphite and/or molybdenum disulfide. The coating is laminated or glued. The coating is provided as a polymer film, preferably polytetrafluoroethylene, Kapton (RTM: Polyimide film) and/or polyester. The coating is designed as a screen-printing coating. The screen coating comprises slide-enhancing additives in the form of graphite, polytetrafluoroethylene, molybdenum disulfide, wax, fluorinated wax, silicone and/or silicone oil. The sealing device is designed as a structuring of the end plate and/or the terminal bipolar plate. The structuring is produced by removing processes, preferably grinding, lapping, polishing and/or honing. The sealing device contains a sealing element which additionally contains an intermediate plate that is arranged such that the sealing element is slidably arranged on the intermediate plate. The intermediate plate is arranged between end plate and the terminal bipolar plate. The thermal expansion coefficient of the intermediate plate is identical to the thermal expansion coefficients of the terminal bipolar plate. The sealing between the intermediate plate and the end plate occurs by injected and/or inserted, one-piece polymer-based sealing system, preferably in force shunt mode. The intermediate plate extends over the entire area of the terminal bipolar plate or is designed as a frame. The thermal expansion coefficient of the terminal bipolar plate is lower than the thermal expansion coefficient of the end plate. The thermal expansion coefficient of the terminal bipolar plate is 5x 10-6K-1-3x 10-5K-1, preferably 1x 10-5K-1-2x 10-5K-1. The thermal expansion coefficient of the end plate is greater than 2x 10-5K-1, preferably greater than or equal to 5x 10-5K-1. The sealing device is designed such that, while maintaining the sealing function, a lateral compensation is provided by sliding a contact point in the region of terminal bipolar plate and sealing device is provided by up to 8 parts per thousand of the greatest lateral extension of terminal bipolar plate. The sealing device is designed such that it is contacted with a bead of the terminal bipolar plate. At least one additional element is arranged between the end plate and the terminal bipolar plate for height adjustment or power adjustment in the stacking direction. A region with meander-shaped, parallel, rectilinear, linear and/or wave-shaped channels is arranged in an electrochemically active region of the terminal bipolar plate. The end plate is made of plastic in terms of weight and/or volume, and has an end plate-base body made of plastic. The intermediate plate is a current collector plate and/or the terminal bipolar plate which is made of metal. The terminal bipolar plate is designed as a metal stamping part. The end plate has through holes for supplying fluids to terminal bipolar plate. At least one of these through holes does not contain a reinforcing insert. At least one of these through holes has a reinforcing insert, which does not extend over full height of the end plate. The electrochemical system has two end plates adjacent to it, and contains a terminal bipolar plate and many bipolar plates. The electrochemical system is a fuel cell system, an electrochemical compressor or an electrolyzer.