Development and performance of a rechargeable thin-film solid-state microbattery

A thin-film solid-state Li/TiS2 microbattery has been developed at Eveready Battery Company (EBC). It is fabricated using sputtering for deposition of the metal contacts, TiS2 cathode, and oxide/sulfide glassy electrolyte. High vacuum evaporation is used to deposit a LiI layer and Li anode. EBC Microbatteries range from 8 to 12 μm in thickness and have a capacity between 35 and 100 μAh/cm2, depending on the amount of anode and cathode deposited. The microbattery open-circuit voltage is approximately 2.5 V. EBC Microbatteries routinely go more than 1000 cycles between 1.4 and 2.8 V, with greater than 90% cathode utilization, at current densities as high as 300 μA/cm2. Several EBC Microbatteries have gone over 10 000 cycles at 100 μA/cm2 with greater than 90% cathode utilization on each cycle. The microbatteries will cycle at temperatures as low as −10 °C at a current density of 100 μA/cm2, are capable of supplying pulse currents of several mA/cm2, and have excellent long-term stability both on shelf and while cycling. Sets of five microbatteries have been assembled in either a series or parallel configuration and cycled more than 1000 times. EBC Microbatteries as large as 10 cm2 have been fabricated and cycled over 1000 times at close to 100% cathode efficiency.