Solution based processing of garnet type oxides for optimized lithium-ion transport

Schwanz, Derek K.W. M.S.M.S.E., Purdue University, August 2016. Solution Based Processing of Garnet Type Oxides for Optimized Lithium-ion Transport. Major Professor: Ernesto E. Marinero. Current lithium based portable electrochemical storage devices are limited by the inherent instability and volatility of conventional electrolytes materials. Ceramic materials show much promise for use in advanced lithium based battery systems due to their inhibition of dendritic growth and high thermal and chemical stability. The main drawback of solid materials is their low ionic conductivity, relying on lattice hopping to transport ions between electrodes during cycling. Garnet type oxides, specifically of the base compositions Li7La3Zr2O12 and Li5La3Bi2O12 have been synthesized through Pechini method solution based processing by the dissolution of reagent salts into nitric acid and creation of a chelated polymerized complex. Through an extensive examination of the subsequent processing conditions, it is revealed that the many contributing factors in this process can be optimized to create mixtures of these two structures. By changing the composition, the structure-property relationships between Li7-xLa3Zr2-xBixO12 compounds are examined demonstrating that stoichiometric variations offer improvements to both the degree of sintering and the ionic transport in this promising class of materials.