Certain embodiments disclosed herein pertain to methods and apparatus for electrodepositing material on a substrate. More particularly, a novel membrane for separating the anode from the cathode/substrate, and a method of using such a membrane are presented. The membrane includes at least an ion exchange layer and a charge separation layer. The disclosed embodiments are beneficial for maintaining relatively constant concentrations of species in the electrolyte over time, especially during idle (i.e., non-electroplating) times.