Mechanical behavior of a battery separator in electrolyte solutions

► The tensile, creep and dynamic behavior of a PP separator in electrolyte solutions were investigated. ► All three measurements indicate that the separator is much softer in solutions. ► The MD stiffness of the separator in solutions is only about a half of that measured in air. ► In the linear viscoelastic range, the creep tendency of the separator may be twice as high in solutions. ► Samples that had been soaked in solutions and tested in air later are insufficient to represent the behavior in solutions.