The present invention provides a battery cell, comprising: (a) an anode comprising an active metal or a metal ion storage material (e.g., an intercalation compound that accommodates lithium ion); (b) a cathode structure; and (c) an ionically conductive protective layer on a surface of the anode and interposed between the anode and the cathode structure. This protective layer comprises a porous membrane having pores therein and a soft matter phase disposed in at least one of the pores, wherein the soft matter phase comprises oxide particles dispersed in a non-aqueous alkali, alkaline, or transition metal salt solution. Most preferably, this battery cell is a lithium metal secondary cell that is essentially free from dendrite and exhibits a safer and more stable cycling behavior. Such a high-capacity rechargeable battery is particularly useful for powering portable electronic devices and electric vehicles.