Numerical and experimental analysis of heat sealing of multi-layered laminate films used in lithium polymer battery packaging

The packaging of a lithium polymer secondary battery involves a wrapping process of an aluminum/polymer laminate film that uses heat sealing. Heat sealing time and sealing block width are important variables in creating packaging requirements for optimal battery performance and safety. In this study, a heat transfer analysis is performed using finite element method to investigate the temperature distribution of the sealing block over the course of the heat sealing process. Heat sealing time and sealing block width were the variables of interest for the heat transfer simulation in order to identify optimal manufacturing conditions. Through the analysis, we successfully identified a minimum heat sealing time less than 3 s and 1.5 mm width of the sealing block that optimizes both the rate of battery production and lithium polymer battery capacity. To validate the quality of heat sealing properties, visual inspection and restrained packaging tests were performed.