In accordance with at least selected embodiments, novel or improved porous membranes or substrates, separator membranes, separators, composites, electrochemical devices, batteries, methods of making such membranes or substrates, separators, and/or batteries, and/or methods of using such membranes or substrates, separators and/or batteries are disclosed. In accordance with at least certain embodiments, novel or improved microporous membranes, battery separator membranes, separators, energy storage devices, batteries including such separators, methods of making such membranes, separators, and/or batteries, and/or methods of using such membranes, separators and/or batteries are disclosed. In accordance with at least certain selected embodiments, a separator for a battery which has an oxidation protective and binder-free deposition layer which is stable up to 5.2 volts or more, for example, up to 7 volts, in a battery is disclosed. The deposition layer is preferably a thin, very thin or ultra-thin deposition on a polymeric microporous membrane applied via a binder-free and solvent-free deposition method. By employing such an ultra-thin deposition layer, the energy density of a battery may be increased. In accordance with at least particular embodiments, the battery separator membrane described herein is directed to a multi-layer or composite microporous membrane battery separator which may have excellent oxidation resistance and may be stable in a high voltage battery system up to 5.2 volts or more. In accordance with at least other certain selected embodiments, the present invention is directed to a separator for a battery which has a conductive deposition layer which is stable up to at least 5.2 volts or higher in a battery.