Investigation of the influence of different bracing of automotive pouch cells on cyclic liefetime and impedance spectra

Lithium-Ion pouch cells are types of cells with great potential regarding energy and power densities to design of battery systems and battery modules in electromobility. These cells pose a high demand on their placement and bracing in the module to compensate their expansion and therefore guarantee a long lifetime. The challenge is to identify optimal bracing for the individual pouch cells. Thus, this work studies the cyclic aging of four identical automotive pouch cells under different bracing conditions while measuring cell-specific force, distance and impedance parameters. This measurement shows an improved mechanical integration of this type of battery cell in modules. Furthermore there is a recognizable correlation between the different conditions of strain and the impedance spectra along different states of aging. From this results a specific parameter is identified which can be used for rapid test procedures.