Addition of a thin-film inorganic solid electrolyte (Lipon) as a protective film in lithium batteries with a liquid electrolyte

Three rechargeable lithium cells have been fabricated using thin films of Li and sputter-deposited LixMn2−yO4 as the electrodes, and a LiPF6 organic liquid electrolyte. Cells were cycled up to 18 times between 4.5 and 2.5 V at 25°C both with and without the addition of the thin-film lithium phosphorus oxynitride solid electrolyte, known as Lipon. Of the cells tested, the Lipon film was most effective in maximizing the capacity and cycling efficiency when deposited in direct contact with the cathode; however, a significant improvement over the Lipon-free cell was also observed with Lipon sandwiched between layers of the liquid electrolyte. In the latter case, the Lipon was deposited onto a microporous polypropylene separator membrane.