Mechanical and electrical properties of a LiCoO2 cathode prepared by screen-printing for a lithium-ion micro-battery

A thick-film cathode was fabricated by a screen-printing technique using LiCoO2 paste to improve the discharge capacity in lithium-ion micro-batteries. A LiCoO2 thick film (approximately 6 μm) was formulated by screen-printing using ethyl-cellulose-based paste. As the adhesion force between the printed cathode and substrate was very weak, delamination was observed during the evaporation of a Li anode on a lithium phosphorous oxynitride (LiPON) solid electrolyte. In order to enhance the adhesion force, a small amount of epoxy was added to the ethyl-cellulose-based LiCoO2 paste. The printed cathode developed in this work showed a typical discharge curve of a LiCoO2 cathode with a discharge capacity close to the theoretical value when the cell was tested using an organic electrolyte. The assembly of an all-solid-state micro-battery with a stable open-circuit voltage (OCV) free from delamination or electrical problems is possible using LiPON solid electrolyte and Li evaporated onto printed LiCoO2 cathode thick films. The printed LiCoO2 thick film was shown to be a potential candidate for cathodes of all-solid-state micro-batteries, despite the fact that a low discharge capacity was obtained in this work.