Influence of sintering additives on densification and Li + conductivity of Al doped Li 7 La 3 Zr 2 O 12 lithium garnet

• Published in: RSC advances Vol. 4; no. 93; pp. 51228 - 51238
• Main Authors: Janani, Narayanasamy, Deviannapoorani, C., Dhivya, L., Murugan, Ramaswamy
• Format: Journal Article
• Language: English
• Published: 2014
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/C4RA08674K

Garnet-like structured solid electrolyte Li 7 La 3 Zr 2 O 12 (LLZ) in the cubic phase has received unique attention due to its high total (bulk + grain-boundary) Li + conductivity combined with good chemical stability against lithium metal and commercial electrodes. In addition to the stabilization of high Li + conductive cubic phase, the dense microstructure related to grains and grain-boundaries is also a critical issue for the successful application of LLZ as solid electrolyte membrane in all-solid-state lithium and lithium–air batteries. In this work, preparation of high Li + conductive 0.9 wt% Al doped cubic LLZ i.e. Li 6.16 Al 0.28 La 3 Zr 2 O 12 (Al–LLZ) by modified sol–gel technique and the influence of sintering additives on the density and total (bulk + grain-boundary) Li + conductivity of the Al–LLZ are investigated. The present work reveals that among the three chosen sintering additives Li 3 BO 3 , Li 3 PO 4 and Li 4 SiO 4 , Li 4 SiO 4 appears to be a better sintering additive for the enhancement of the total (bulk + grain-boundary) Li + conductivity and density of Al–LLZ. Among the investigated samples, Al–LLZ with 1 wt% of Li 4 SiO 4 added and sintered at 1200 °C exhibits maximized total (bulk + grain-boundary) Li + conductivity of 6.1 × 10 −4 S cm −1 at room temperature (33 °C) along with the maximized density of 4.86 g cm −3 (relative density of 96%).