A method and apparatus for making thin-film batteries having composite multi-layered electrolytes with soft
electrolyte between hard
electrolyte covering the negative and / or positive
electrode, and the resulting batteries. In some embodiments, foil-core
cathode sheets each having a
cathode material (e.g., LiCoO2) covered by a hard
electrolyte on both sides, and foil-core
anode sheets having an
anode material (e.g.,
lithium metal) covered by a hard electrolyte on both sides, are laminated using a soft (e.g.,
polymer gel) electrolyte sandwiched between alternating
cathode and
anode sheets. A hard glass-like electrolyte layer obtains a smooth hard positive-
electrode lithium-
metal layer upon charging, but when very thin, have randomly spaced pinholes / defects. When the hard
layers are formed on both the positive and negative electrodes, one
electrode's
dendrite-short-causing defects on are not aligned with the other electrode's defects. The soft electrolyte layer both conducts ions across the gap between hard electrolyte
layers and fills pinholes.