Li _6.6 Al _0.05 La ₃ Zr _1.75 Nb _0.25 O ₁₂ thin film solid electrolyte synthesized by electrophoretic deposition

The development of solid-state lithium-ion power sources is currently hindered by technological barriers including high resistance at the interface between the solid electrolyte and electrodes and complex manufacturing process. Thin films of solid electrolyte reduce ionic resistance by minimizing structural defects and increasing the contact area between the electrodes and the electrolyte. The present work investigates the structure, morphology and lithium-ion conductivity of Li6.6Al0.05La3Zr1.75Nb0.25O12 films synthesized on a Ti substrate by electrophoretic deposition. The effect of the pre-synthesis processing of the solid electrolyte powder on the final film properties is studied by comparing initial powders of Li6.6Al0.05La3Zr1.75Nb0.25O12 solid electrolyte annealed at a final temperature of 900 °C and 1150 °C. It is shown that milling the initial solid electrolyte powder improves the structure of the final film. The films had a homogenous structure with a thickness of 40–60 μm. The film produced from the powder with the final annealing temperature of 1150 °C and annealed at 300 °C delivered the highest conductivity among the samples investigated (3.4·10–6 S·cm–1 and 4.5·10–5 S·cm–1 for through- and in-plane conductivity, respectively, at 300 °C).