STUDIES ON MEMBRANE FOR REDOX FLOW BATTER Y .4. CROSS-LINKING OF THE MEMBRANE BY THE ELECTRON-RADIATION AND DURABILITY OF THE MEMBRANE

Chlorosulfonated homogeneous and asymmetric cation exchange membranes were tested as separators for the all-vanadium redox flow battery. The membrane was prepared by chlorosulfonation of the polyethylene film i n vapour phase. In the case of the polyethylene film of 20 mu m thickn ess used for the homogeneous membrane, area resistivity of 0.5 Omega . cm(2) in 2M KCl aq. solution was reached at 120 min. chlorosulfonatio n time, In the case of heat laminated 20 mu m thick PE film on a neutr al porous polyolefin film of 200 mu m thickness used for the asymmetri c membrane, a minimum area resisitivity of 1 Omega . cm(2) in 2M KCl w as achieved at 120 min. chlorosulfonation time, The performance evalua tion of the membranes as separators in the all-vanadium redox flow bat tery was also measured. The area resistivity of the membranes in the m easuring-cell using charge-discharge current density 63.7 mA/cm(2) was 1.4 Omega . cm(2) and 2.2 Omega . cm(2) for charge and discharge resp ectively for the homogeneous membrane, and 3.6 Omega . cm(2) and 4.3 O mega . cm(2) for charge discharge cycles respectively for the asymmetr ic membrane. The chlorosulfonated homogeneous cation exchange membrane was cross-linked by the electron radiation to improve durability of t he membrane. The crosslinked membrane which has the high degree of cro ss-linking, did not shown the mechanical breakage by swelling or shrin king in the acidic vanadium solution, but its area resistivity in the all-vanadium redox flow battery was increased.