Achieving enhanced densification and superior ionic conductivity of garnet electrolytes via a co-doping strategy coupled with pressureless sintering. Issue 12 (September 2022)

• Record Type: Journal Article
• Authors: Song, Xin; Zhang, Tianhang; Christopher, Timothy D.; Guo, Yong; Huang, Saifang; Liu, Yangai; Söhnel, Tilo; Cao, Peng
• Is Part Of: Journal of the European Ceramic Society. Volume 42:Issue 12(2022)
• Page Start: 5023
• Page End: 5028
• Publication Date: 2022-09
• Subjects: Solid-state electrolytes -- Garnet-type oxide -- Ionic conductivity -- Pressureless sintering -- Densification; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2022.04.059
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: Lithium garnet oxides with 6.5 mol Li, such as Li6.5 La3 Zr1.5 (Ta/Nb)0.5 O12, typically crystallise in cubic structure and exhibit excellent room-temperature ionic conductivity close to 1 mS cm −1 . However, it is challenging to densify garnet oxides. In this work, we investigated how the co-doping of tantalum (Ta) and niobium (Nb) affects the densification of pressureless sintered garnet electrolytes with compositions of Li6.5 La3 Zr1.5 Ta(0.5−x) Nbx O12, where x = 0–0.5. The highest densification (94.5% of relative density) was achieved in Li6.5 La3 Zr1.5 Ta0.1 Nb0.4 O12 (TN-LLZO) when it was sintered at 1150 °C for 6 h. This TN-LLZO garnet electrolyte delivers an ionic conductivity of 1.04 × 10 −3 S cm −1 (at 22 °C) with a low activation energy of 0.41 eV. Our findings demonstrate that the content of dopants (Ta and Nb) plays a critical role in enhancing the sintering performance of garnet ceramics at ambient pressure.