In an embodiment, a metal-organic framework electrolyte layer, can comprise a plurality of metal-organic frameworks having a porous structure and comprising a solvated salt absorbed in the porous structure; and a polymer. The MOF electrolyte layer can have at least one of a density of less than or equal to 0.3 g/cm3 or a Brunauer-Emmett-Teller surface area of 500 to 4,000 m2/g. A lithium metal battery can comprise the metal-organic framework electrolyte layer.