NOVELTY - Microporous layer (I) comprises a microporous xerogel comprising pores that are substantially continuously interconnected from a first outermost surface of the microporous xerogel through to a second outermost surface of the microporous xerogel and a crosslinked polymer binder comprising a polymer having a glass transition temperature of 50 degrees C or higher, where the polymer binder is water soluble prior to crosslinking.    USE - (I) is useful in separator layer for an electrochemical cell made and separator membrane for a lithium battery. (I) is useful in an article (all claimed), where the article is e.g. electrochemical cells, capacitors, fuel cells, ink jet printing and other imaging media, and filtration media.    ADVANTAGE - (I) has: high glass transition temperature which is maintained in the presence of chemicals such as water and/or electrolyte; and improved thermal and chemical resistance. (I) enhances mechanical strength and flexibility to the microporous layer assembly.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a method of manufacture of (I) having a microporous xerogel, comprising disposing onto a substrate a xerogel-forming composition comprising a sol, a binder comprising a crosslinked polymer having a glass transition temperature that is greater than or equal to 50 degrees C, where the polymer binder is water soluble prior to crosslinking, and a liquid medium, removing the liquid medium from the xerogel-forming composition to form the microporous xerogel and contacting a surface of the microporous xerogel with an organic electrolyte, and infusing the organic electrolyte into pores of the microporous layer; and    (2) a separator membrane for a lithium battery, comprising at least one layer of a microporous xerogel comprising an inorganic material and a crosslinked polymeric binder, and the pores that are substantially continuously interconnected from a first outermost surface of the separator membrane through to a second outermost surface of the separator membrane, where the separator membrane has a porosity of 20-80%, and the crosslinked polymeric binder is water-soluble prior to crosslinking.