Spray layer-by-layer with catechol-modified polymer for Li anode protective layers

Battery separators for lithium-air batteries are provided. In some embodiments, a lithium-air battery may comprise one or more electrochemical cells including an anode, a cathode, an electrolyte, and a battery separator positioned between the anode and the cathode. The battery separator may comprise a porous membrane having a lithium ion conductive film on at least a portion of the porous membrane. The lithium ion conductive film may comprise layers designed to impart beneficial properties to the porous membrane and/or battery, such as resistance to dendrite formation, while having relatively minimal or no adverse effects on one or more important properties of the porous membrane (e.g., ionic conductivity, electrolyte permeability, weight, mechanical stability) and/or the overall battery. The respective characteristics and number of the layers in the lithium ion conductive film may be selected to impart desirable properties to the battery separator and/or the battery while having relatively minimal or no adverse effects.