Stability of garnet-type solid electrolyte LixLa3A2-yByO12 (A=Nb or Ta, B=Sc or Zr)

• Published in: Solid state ionics Vol. 282; pp. 7 - 12
• Main Authors: Nemori, H., Matsuda, Y., Mitsuoka, S., Matsui, M., Yamamoto, O., Takeda, Y., Imanishi, N.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2015
• Subjects: Garnet-like lithium ion conductor; Li6.25La3A2 -xBxO12 (A = Nb5 + or Ta5 +, B = Sc3 + or Zr4 +); Water-stable lithium ion conductor; Water-stable lithium ion conductor; Li6.25La3A2-xBxO12 (A=Nb5+ or Ta5+, B=Sc3+ or Zr4+); Garnet-like lithium ion conductor
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/j.ssi.2015.09.015

Garnet-type solid electrolytes LixLa3A2-yByO12 (A=Nb5+ or Ta5+, B=Sc3+ or Zr4+) were examined with respect to their stability in contact with lithium metal, water, and a liquid electrolyte for application in an aqueous lithium-air secondary battery. Electrolyte samples were synthesized by a solid state reaction method using a magnesia rather than alumina crucible to avoid aluminum contamination. The garnet-type electrolytes including Zr4+ ions exhibited higher ionic conductivity than those with Sc3+ ions. The electrolytes including Ta5+ were stable in contact with lithium metal, whereas those with Nb5+ were not. Lithium ions in all the samples were partly proton-exchanged in distilled water; however, the garnet-like structure remained unchanged as reported in many papers. In contrast, all the electrolyte samples were stable in the aqueous solution of 10M LiCl and 2M LiOH (suitable electrolyte for aqueous Li-air battery system). The garnet-type lithium ion conductors comprising Zr4+ and Ta5+ ions were revealed to be suitable for use as the protective membrane between the lithium metal electrode and aqueous electrolyte in rechargeable lithium-air batteries. •Garnet-like Li6.25La3A2-xBxO12 (A=Nb5+ or Ta5+, B=Sc3+ or Zr4+) were synthesized.•The samples composed of Ta showed high stability to lithium metal.•The samples were easily proton-exchanged in water.•The samples were stable against an electrolyte for aqueous Li-air battery system.