Sol–gel processing of Li1.5Al0.5Ti1.5(PO4)3 solid electrolyte thin films via polymeric complex precursor

• Published in: Journal of sol-gel science and technology Vol. 79; no. 3; pp. 564 - 572
• Main Authors: Takase, Satoko, Kubo, Chie, Aono, Ryota, Shimizu, Youichi
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.09.2016; Springer Nature B.V
• Subjects: Ceramics; Chemistry and Materials Science; Citric acid; Composites; Electrolytes; Glass; Inorganic Chemistry; Ion currents; Lithium; Lithium ions; Materials Science; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper: Functional coatings; pH control; Polymer films; Prepolymers; Sol-gel processes; Solid electrolytes; Thin films; thin films and membranes (including deposition techniques); LATP; Polymer precursor; Solid electrolyte; Lithium ion conductor; Thin film
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-016-4043-y

Thin films of crack-free lithium ionic conductive Li 1.5 Al 0.5 Ti 1.5 (PO 4 ) 3 (LATP) solid electrolyte could be fabricated by a modified Pechini-type polymeric precursor method with controlled amount of citric acid (CA), pH, and viscosity of precursor at low temperatures between 600 and 700 °C. It turned out that the increase in molar ratio of citric acid to total metal salts ( M ) in the precursor gave drastic change of thermal reactions and crack-free LATP thin films could be obtained from the precursor with CA/ M  = 5. In addition, the formation of LATP crystal phase required the viscosities more than 0.100 Pa s. It was also found that the pH control of the coating solutions was a key step to obtain homogeneous thin films. FT-IR measurements revealed that the change of pH in the precursors gave structural changes in precursor complexes. The LATP thin film of 200 nm in thickness prepared from the solution at CA/ M  = 5, 0.100 Pa s, and pH = ca. 10, sintered at 650 °C showed an ionic conductivity of ca. 0.029 S/cm at 300 °C. Graphical Abstract