Aqueous tape casting of titanium-doped lithium metazirconate (Ti-Li₂ZrO₃) sheets for solid-state electrolyte applications

Abstract

Ti-doped lithium zirconate (LZTO) sheets were successfully made by aqueous tape casting, by starting from an innovative colloidal synthesis route and optimizing the colloidal processing parameters. Zeta potential and particles size measurements, together with rheological characterization, were performed to adjust the slip composition. Then, the suspension with 1.0 wt% of ammonium polyacrylate dispersant (APA) and solid loading of 31 vol.% resulted in flat and flexible sheets, thinner than 450 μm, by adding 20 wt% of acrylic binder emulsion. After annealing at 1150 ◦C/15 h, LZTO sheets densified up to 85.5 %, presented a microstructure with grains of 6.4 μm in diameter, and exhibited electrical conductivity values in the order of 10⁻⁷, 10⁻⁶ and 10⁻⁵ S⋅cm⁻¹ at 350, 450 and 600 ◦C, respectively. Besides, XRD phase analysis revealed monoclinic Li₂ZrO₃ and minor ZrO₂ impurities originated from Li₂O volatilization during sintering, but no sign of TiO₂ segregation, indicating the formation of Li₂Zr₁-ₓTiₓO₃ solid solution.