Batteries were assembled by pressing 5 mg of the cathode composite and 20 mg of the anode composite on either side of a 200 mg layer of the solid electrolyte at 460 MPa for 90s. For FATO-based composites, a piece of gold leaf (24 carat) was then pressed onto the cathode surface to reduce the contact resistance between the pellet and the stainless-steel current collector. In case of the cells operated with applied stack pressure, gold leaf was also applied to cathodes of the FATO-and the Super P-based cells to avoid corrosion of the current collector as observed in an earlier publication .