Developments of high-voltage all-solid-state thin-film lithium ion batteries

Powders of Li2MMn3O8 (M = Fe, Co) were prepared by glycine nitrate combustion from the corresponding metal nitrates. The reaction products were pressed into pellets with the addition of 20 wt.% excess LiNO3, which were used as targets for e-beam evaporation. A high-voltage all-solid-state thin-film lithium ion battery was demonstrated by the sequential deposition of spinel structured Li2MMn3O8 (M = CO, Fe) as positive electrode by e-beam evaporation, LiPON as electrolyte, and metallic A] as negative electrode by sputtering in N-2 and Ar gas mixtures with specific power and gas flow rates. A lithium ion conductivity of similar to 10(-6) S cm(-1) was observed for the optimized thin-film UPON electrolyte prepared under the condition of a chamber pressure of 2.6 x 10(-2) mbar and a power of 60-100 W. The chemical diffusion coefficient A was found to be in the range 10(-13) to 10(-12) cm(2) s(-1) for any composition x of Li2-xMMn3O8 (M = Fe, Co) in the range from 0.1 to 1.6 by employing the galvanostatic intermittent titration technique (GITT). AC impedance studies revealed a charge transfer resistance of 260-290 Omega, a double layer capacity of similar to 45-70 mu F for an electrode area of 6.7 cm(2). (c) 2005 Elsevier B.V. All rights reserved.