Abstract
We present combinatorial method for high-throughput screening and synthesis of libraries of solid lithium-ion conductors. The method has the advantages of speed, simplicity and the capability to produce and control simultaneously a variety of compositions by the co-deposition on a substrate of several different materials to create "materials library".
In our research we fabricate materials libraries by two methods. The first one is RF-magnetron sputtering, where Ar plasma sputters a target material that is being deposited on a substrate. The effects of RF power applied to Li2O and LiAlSiO2 targets, the deposition time, rotation of the substrate and heat treatment on Li-ion conductivity of 169 samples of one library have been studied. The XPS tests showed that RF coating contains Li2O, Li2CO3, LiAl0.18Si0.13O1.22, LiAl0.67Si0.41O2.49 and LiAl1.17Si0.71O3.93 compounds. The non-stoichiometric lithium aluminum silicates are amorphous as displayed in the XRD patterns. The room-temperature conductivity of sputtered about 350nm-thick LiAlxSiyOz film varies from 10-8 to 10-7S/cm depending on the stoichiometry. The conductivity vs. temperature plots show Arrhenius behavior. The activation energy found for the bulk conductivity is 22kJ/mol and for the grain boundaries- 55kJ/mol. The substrate morphology influences the fabricated film morphology and grain boundaries conductivity.
The second method is spray pyrolysis, based on simultaneous spraying of different precursors solutions from a multi-head nozzle on a substrate. This is followed by pyrolysis and oxidation. The preparation of multi-component solid electrolytes library by spray pyrolysis is a novel approach. Despite relatively low density of the LixLayPO4 ceramics, preliminary ionic conductivities, were found to vary from 2*10-7 to 4*10-5 S cm−1.