NOVELTY - A battery cell comprises an anode comprising an active metal or a metal ion storage material; a cathode structure; and an ionically conductive protective layer on a surface of the anode and interposed between the anode and the cathode structure. The protective layer comprises a porous membrane having pores in the membrane and a soft matter phase disposed in at least one of the pores, where the soft matter phase comprises oxide particles dispersed in a non-aqueous alkali, alkaline, or transition metal salt solution.    USE - As a battery cell such as lithium metal battery cell and lithium ion battery cell useful in a battery (claimed) useful as power source for electric vehicle (EV) e.g. electric car, hybrid electric vehicle (HEV), and portable electronic devices, such as lap-top computers and mobile phones.    ADVANTAGE - The anode protective layer or combined protective/electrolyte layer is effective in suppressing dendrite formation. The anode protective layer enables the utilization of a lithium (Li) metal secondary battery that exhibits the highest reversible capacity and a stable cycling behavior. The soft matter anode protective layer has high metal ion conductivity which is higher than that of a corresponding metal salt solution alone and is capable of stopping dendrite penetration. With such high Li ion conductivity, the protective layer can also serve as a separator-electrolyte layer in a Li metal or Li ion battery. By impregnating the soft matter phase in a porous membrane with proper pore sizes and porosity levels, the resulting protective layer becomes very effective in blocking dendrite penetration while still providing impressive ion conductivity. The protective layer technology significantly improves the safety and cycling stability of Li metal batteries by suppressing Li dendrite propagation. The battery cell is free from dendrite and exhibits a safer and more stable cycling behavior.    DETAILED DESCRIPTION - A battery cell comprises an anode comprising an active metal or a metal ion storage material; a cathode structure; and an ionically conductive protective layer on a surface of the anode and interposed between the anode and the cathode structure. The protective layer comprises a porous membrane having pores in the membrane and a soft matter phase disposed in at least one of the pores, where the soft matter phase comprises oxide particles dispersed in a non-aqueous alkali, alkaline, or transition metal salt solution. The conductive protective layer serves as a separator or electrolyte layer disposed between the anode and the cathode structure.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of battery cell having an anode protective layer and a separate electrolyte-separator layer.