A THIN-FILM SOLID-STATE MICROBATTERY

A functional thin-film 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, cathode, and oxide-sulfide solid electrolyte; high vacuum vapor deposition is used for a LiI layer and Li anode. The completed microbattery has an overall thickness of approximately 10 mum 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 cuttoff at current densities ranging from 10 to 135 muA/cm2. The microbattery is capable of supplying current pulses of two seconds duration at current densities greater than 2 mA/cm2. 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.