In this paper, we simulated the heat transfer and heat sealing processes of a lithium polymer battery package using finite element method (FEM). We observed and calculated the temperature change of an aluminum (Al) laminate thin film and sealing block during different sealing times. We also calculated the temperature change of the sealing block during consecutive heat sealing processes. For the design of the sealing block for the manufacturing process, we set the heat sealing time and area of the sealing block of the lithium polymer battery packaging as variables in heat transfer analysis. We succeeded in predicting effective heat transfer behavior and calculating the heat loss in consecutive heat sealing processes in numerical values.

The heat-sealing strength of pouch film greatly affects the reliability of the lithium ion secondary battery. In this paper, the researchers investigated and evaluated the properties of the heat-sealing strength of pouch film, such as heat, pressure, time, thickness of the heat-seal, and the polypropylene material. The heat-sealing strength showed a high value at 180℃ for 3 seconds. However, under the conditions of higher temperatures and longer times, deformation and bulging of polypropylene were observed. The heat-sealing strength tended to increase when decreasing heat-seal thickness. The heat-sealing strength varied according to the type of polypropylene. In addition, to avoid defects that may have occurred in the process of manufacturing the lithium ion secondary battery, the heat-sealing strength in the state where the impurities remained was evaluated.