Macroporous polymer separators based on poly(vinylidene fluoride) (PVdF) and several VdF copolymers were prepared by a phase inversion process using acetone as a solvent. The resulting macroporous separators were characterized in terms of morphology, swelling behaviour, thermal and mechanical properties and ionic conductivity. The PVdF separator had a highly porous structure (80%) and exhibited good mechanical properties. Once filled by a molar solution of tetraethylammonium tetrafluoroborate (TEABF(4)) in acetonitrile (AN) it provided enhanced conductivity (18 mS cm(-1) at 25 degrees C) compared with commercial cellulose and Celgard (TM) separators. (C) 2011 Elsevier Ltd. All rights reserved.