The Impact of Lithium Tungstate on the Densification and Conductivity of Phosphate Lithium‐Ion Conductors. Issue 5 (23rd December 2021)

• Record Type: Journal Article
• Authors: Odenwald, Philipp; Ma, Qianli; Davaasuren, Bambar; Dashjav, Enkhtsetseg; Tietz, Frank; Wolff, Michael; Rheinheimer, Wolfgang; Uhlenbruck, Sven; Guillon, Olivier; Fattakhova‐Rohlfing, Dina
• Is Part Of: ChemElectroChem. Volume 9:Issue 5(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-23
• Subjects: Ceramics -- Crystal growth -- Lithium-ion conductor NASICON-type -- Solid electrolyte; Electrochemistry -- Periodicals; 541.37
• DOI: 10.1002/celc.202101366
• Languages: English
• ISSNs: 2196-0216

Abstract

Abstract: Phosphate lithium‐ion conductors are outstanding electrolyte materials for solid‐state lithium batteries. As polycrystalline ceramics, they must be sintered at high temperatures. Lithium tungstate Li2 WO4 (LWO) is reported for the first time as an effective sintering aid to reduce the sintering temperature for one of the most common solid‐state lithium‐ion conductors, Li1.5 Al0.5 Ti1.5 (PO4 )3 (LATP). While densification of LATP without sintering aids requires temperatures of at least 950 °C to obtain a relative density of 90 %, here relative densities of 90–95 % are achieved even at 775 °C when 5 wt.% of LWO are added. At 800 °C the LATP containing 5–7 wt.% LWO densifies to a relative density of 97.2 %. The ionic conductivity of LWO containing LATP is generally higher than that of pure LATP sintered at the same temperature. LATP containing 7 wt.% LWO shows high ionic conductivity of 4.4×10 −4 S/cm after sintering at 825 °C. A significant reduction in sintering temperature, an increase in density and in the ionic conductivity of LATP as well as its non‐toxicity render LWO a very promising sintering aid for the development of LATP‐based solid state batteries. Abstract : Sintering at lower temperatures : With the addition of Lithium tungstate LATP the sintering temperatures can be decreased by 100 K while achieving higher relative densities and increased ionic conductivities (4.4×10 −4 S/cm). In this paper the influence on the phase composition and microstructure is investigated. It shows the formation of eutectic melt during sintering and the formation of a WO3 ‐phase at the grain boundary.