A thin film solid state microbattery

Abstract

A functional thin film solid state microbattery has been developed at the Technology Laboratory of Eveready Battery Company (EBC). The microbattery is constructed using cathode sputtering for deposition of the contacts, TiS 2 cathode, and oxide-sulfide solid electrolyte; while high vacuum vapor deposition is used for a LiI layer and Li anode. The completed microbattery has an overall thickness of approximately 10μm and an open circuit voltage near 2.5 V. On the primary discharge the microbattery shows close to 100% cathode utilization (based on a one electron change) to a 1.8 V cutoff at current densities ranging from 10–135 μA/cm 2. The microbattery is capable of supplying current pulses of two seconds duration at current densities greater than 2 mA/cm 2. The microbattery also shows excellent secondary performance. Cells routinely give over 1000 cycles of 100% cycling efficiency (discharge capacity equal to the charge capacity) at greater than 70% cathode utilization on each cycle.