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The Effect of Different La-Containing Starting Materials on the Synthesis, Sintering, and Li⁺-Conductivity of Li_3xLa_2/3-xTiO₃

A.C. Sutorik¹, C. Cooper¹, M.D. Green¹, J. Wolfenstine², G. Gilde¹

¹ U.S. Army Research Laboratory, RDRL WMM E, Building 4600, Aberdeen Proving Ground, D 21005, USA
² U.S. Army Research Laboratory, RDRL SED C, 2800 Powder Mill Road, Adelphi, MD 20783, USA

received September 20, 2012, received in revised form November 1, 2012, accepted November 9, 2012

Vol. 4, No. 2, Pages 59-68   DOI: 10.4416/JCST2012-00035

Abstract

Li_3xLa_2/3-xTiO₃ is a promising ceramic electrolyte for high energy density Li-batteries. The material is usually prepared from solid state reactions between Li₂CO₃, La₂O₃, and TiO₂, but the hydroscopic nature of La₂O₃ leads to inconsistencies in formulation and synthetic outcome which can impact the phase formation and corresponding Li-conductivity of the final ceramic. To address this issue, La carbonate and hydroxides have been evaluated as starting materials for solid state synthesis of Li_3xLa_2/3-xTiO₃ powders and sintered ceramic. The different La-starting materials are all prepared from precipitation reaction as high surface area powders. These are characterized for phase, particle size, particle morphology, and ceramic yield (by thermal gravimetric analysis). The La starting materials are then mixed with the desired stoichiometric amounts of Li₂CO₃ and TiO₂. The mixtures are calcined at 1100 °C for 1 h before being pressed into green parts and sintered at either 1200 or 1300 °C for 6 h. Under nearly all conditions investigated, the formulations using the La-carbonate-based starting material lead to ceramics with the highest bulk density, the highest degree of cubic superstructure formation, and the highest lattice Li⁺-conductivity. Total conductivity, however, appears largely insensitive to the La starting material used.

Keywords

Keywords: Li⁺-conducting ceramic, Li-air battery, ceramic electrolyte, lithium lanthanum titanate

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