Abstract:

 Aluminum plastic composite foil has become the common packaging material for soft package Li-ion battery, so it is worthy to study the influence factors of its heat-sealing strength to optimize safe capacity for battery. In this article, the heat-sealing strength of Al plastic foil after soaking in the electrolyte is tested by universal testing machine to discuss the influence of soaking ways(“soaking thoroughly” and “soaking partly”) and soaking time. It can be concluded that the heat-sealing strength and the failure modes under the different conditions(heat-sealing temperature and heat-sealing time) for “soaking thoroughly” is the same on basic, the achieved strength cannot reflect the real strength of heat-sealing zone. By contrast, the heat-sealing strength for soaking in bags can avoid the influence of the PA lay and the Al foil, so it is the better way to soak. In addition, the heat-sealing strength of Al plastic foil sinks after soaking, of which the trend is especially obvious for the specimens heat-sealed on lower heat-sealing temperature and shorter heat-sealing time. In experiments, it is found that during soaking the PH of electrolyte becomes lower, which may be one of the reasons for the sinking heat-sealing strength mentioned above.

Key words: Li-ion battery, aluminum plastic composite foil, soak, heat-sealing strength