A facile route to thin-film solid state lithium microelectronic batteries

We describe the synthesis and characterization of a thin-film solid state lithium rechargeable battery. This battery was designed for integration into a multi-chip module (MCM). The battery consists of a spin-on Ag2WO4 — polymer cathode, a lithium hexaflurophosphate — polymer-impregnated microporous nylon membrane electrolytic separator, and a lithium foil anode. Kapton™ was used as the substrate and encapsulating top layer of the battery. The battery had a total area of approximately 4.0 cm2, thickness of 0.6 mm, and weighed 0.4 g. The battery had an open circuit voltage of 3.5 V and was able to deliver a current density of 0.05 mA/cm2 for 1.5 h while maintaining a voltage above 2.0 V. The battery was cycled over 12,000 times between 3.5 and 2.0 V using a constant discharging current density of 0.1 mA/cm2 and charging current density of 0.05 mA/cm2. The battery was designed for integration into a standard 96 pin Kovar/Glass Bead quad-flatpack programmable MCM (1.42×1.42×0.16 in.). The charging and discharging characteristics of this battery are presented and discussed in terms of its intended application.