Effect of film properties on formability of aluminum pouch for secondary battery

The present study was conducted to investigate the effect of film properties on the formability of aluminum pouches for secondary batteries. Among the physical properties of the film, the effects of the friction coefficient and the elongation rate on the formability were investigated. The purpose of this study is to draw the improvement of formability according to the physical properties of the films for constructing the aluminum pouch on the assumption that the Friction resistance between the mold and material in the forming process and the Tensile resistance generated when the material is deformed by the punch will affect the formability. The results showed that the formability was better when the friction coefficient was lower. Specially, the formability is improved more in the sample that had the nylon film with a reduced friction coefficient than in the sample with the CPP film that had a reduced friction coefficient. This indicates that the limit of bending deformation was extended as the friction coefficient of the nylon film get lower. In addition, we found that the formability depends on the elongation property. The formability is improved when the nylon film with isotropic property and a CPP film with stable elongation property were applied. In a sample NY.2/CPP.2 manufactured by using an isotropic nylon and a stably elongated CPP film, the formability has maximum forming depth of 5.5 mm. This result verified that materials that have low friction coefficient, isotropy and a stable elongation property may be applied to improve the formability.