| abstract |
(57) [Abstract] [PROBLEMS] To provide a separator for a zinc-bromine secondary battery having excellent heat resistance and stress crack resistance. SOLUTION: This comprises 5% by weight or more of ultrahigh molecular weight polyethylene having a viscosity average molecular weight of 500,000 or more, and is composed of polyethylene having a viscosity average molecular weight of 350,000 or more and finely divided silica, and has a tensile breaking strength in the longitudinal direction of 30 kg / A separator for a zinc-bromine secondary battery, which has a value obtained by dividing the tensile strength at break in the longitudinal direction by the tensile strength at break in the horizontal direction of 0.4 to 3 in cm 2 or more. |