THIN-FILM RECHARGEABLE LI BATTERIES

Thin film rechargeable lithium microbatteries that have previously reported in literature are reviewed. A more detailed discussion of the microbatteries recently developed independently at Eveready Battery Company (EBC) and Bellcore is presented. The EBC microbattery consists of a TiS2 cathode, an oxide-sulfide electrolyte, and a Li anode. It has an OCV near 2.5 V and routinely goes more than 1000 cycles between the limits of 1.8 V and 2.8 V, with greater than 70% cathode utilization, at current densities up to 300 muA/cm2. Also, it can be cycled at - 10-degrees-C at a current density of 100 muA/cm2, is capable of supplying 2 s pulses of several mA/cm2, and has excellent long term stability both on shelf and while cycling. The Bellcore microbattery consists of an LiMn2O4 cathode, a lithium borophosphate (LiBP) or lithium phosphorus oxynitride (LiPON) electrolyte, and a Li anode. It has an OCV near 4.2 V and cycles more than 150 times between 3.5 V and 4.3 V, with nearly 75% cathode efficiency, at current densities up to 70 muA/cm2.