A battery comprises at least one battery cell on a support, the battery cell comprising (i) an electrolyte between a plurality of electrodes, and (ii) a top surface. A protective casing having a barrier layer contacts the top surface of the battery cell, the barrier layer comprising (i) an oxygen permeability or nitrogen permeability that is less than 80 cm3*mm/(m2*day), (ii) a carbon dioxide permeability that is less than 1 cm3*mm/(m2*day), and (iii) a water permeability that is less than 4 g*mm/(m2*day). A conformal coating covers the barrier layer, the conformal coating having a viscosity that is less than about 100,000 Pa-s at about 150° C. A cap is adhered to the conformal coating.