Thin-film electrodes and battery cells, and methods of fabrication. A thin film electrode may be fabricated from a non-metallic, non-conductive porous support structure having pores with micrometer-range diameters. The support may include a polymer film. A first surface of the support is metalized, and the pores are partially metallized to create metal tubes having a thickness within a range of 50 to 150 nanometers, in contact with the metal layer. An active material is disposed within metalized portions of the pores. An electrolyte is disposed within non-metalized portions of the pores. Active materials may be selected to create an anode and a cathode. Non-metalized surfaces of the anode and cathode may be contacted to one another to form a battery cell, with the non-metalized electrolyte-containing portions of the anode facing the electrolyte-containing portions of the cathode pores. A battery cell may be fabricated as, for example, a nickel-zinc battery cell.