Tri-Doping of Sol–Gel Synthesized Garnet-Type Oxide Solid-State Electrolyte

• Main Authors: Minji Kim, Gwanhyeon Kim, Heechul Lee
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Micromachines
• Subjects: solid state electrolyte; all-solid-state battery; lithium-ion battery; garnet oxide; doping; co-doping
• Online Access: https://www.mdpi.com/2072-666X/12/2/134

The rapidly growing Li-ion battery market has generated considerable demand for Li-ion batteries with improved performance and stability. All-solid-state Li-ion batteries offer promising safety and manufacturing enhancements. Herein, we examine the effect of substitutional doping at three cation sites in garnet-type Li₇La₃Zr₂O₁₂ (LLZO) oxide ceramics produced by a sol–gel synthesis technique with the aim of enhancing the properties of solid-state electrolytes for use in all-solid-state Li-ion batteries. Building on the results of mono-doping experiments with different doping elements and sites—Al, Ga, and Ge at the Li⁺ site; Rb at the La³⁺ site; and Ta and Nb at the Zr⁴⁺ site—we designed co-doped (Ga, Al, or Rb with Nb) and tri-doped (Ga or Al with Rb and Nb) samples by compositional optimization, and achieved a LLZO ceramic with a pure cubic phase, almost no secondary phase, uniform grain structure, and excellent Li-ion conductivity. The findings extend the current literature on the doping of LLZO ceramics and highlight the potential of the sol–gel method for the production of solid-state electrolytes.