Gd-doped Li7La3Zr2O12 garnet-type solid electrolytes for all-solid-state Li-Ion batteries. (20th April 2018)

• Record Type: Journal Article
• Authors: Song, Shidong; Chen, Butian; Ruan, Yanli; Sun, Jian; Yu, Limei; Wang, Yan; Thokchom, Joykumar
• Is Part Of: Electrochimica acta. Volume 270(2018)
• Page Start: 501
• Page End: 508
• Publication Date: 2018-04-20
• Subjects: Garnet -- Lithium lanthanum zirconate -- Gd-doped LLZO -- Solid electrolytes -- All-solid-state Li-ion batteries; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2018.03.101
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: Li7 La3 Zr2 O12 (LLZO) garnet is one of the most promising Li-ion solid electrolytes for all-solid-state Li-ion batteries, owing to its high chemical stability against Li metal and relatively high Li-ion conductivity. In order to further enhance the conductivity of LLZO, Gd 3+ is used to dope LLZO at the Zr 4+ site, in order to enable excess Li to occupy the octahedral sites, which could facilitate Li-ion transport and increase ionic conductivity. In this study, Li7+x La3 Zr2-x Gdx O12 (LLZGO, x = 0–0.5) solid electrolytes with cubic phase and high relative densities are prepared at 1220 °C using a solid-state reaction method. It is found that LLZGO garnets with x from 0.1 to 0.2 deliver higher conductivities than pristine LLZO. Among these, the Li7.2 La3 Zr1.8 Gd0.2 O12 (LLZG2O) sample achieves the highest room-temperature total conductivity of 2.3 × 10 −4 S cm −1 . X-ray diffraction characterization confirms that LLZG2O is chemically stable against Li metal at room temperature for half a month. Cyclic voltammetry shows that LLZG2O possesses good electrochemical stability and reversibility of Li dissolution and deposition reactions. Symmetrical cells using a LLZG2O solid electrolyte and two Li metal electrodes are cycled galvanostatically under various current densities. The results demonstrate that the cell can achieve excellent cycling stability and low overpotentials for the dissolution and deposition reactions of Li. The substitution of Gd 3+ for Zr 4+ is effective in improving the Li-ion conductivity of LLZO, and Li7+x La3 Zr2-x Gdx O12 could be promising as solid electrolytes for high-performance all-solid-state Li-ion batteries. Graphical abstract: Highlights: Substitution with Gd 3+ (0.1–0.2 mol) can increase conductivity of Li7 La3 Zr2 O12 . Li7.2 La3 Zr1.8 Gd0.2 O12 demonstrates an excellent stability against Li metal. Li| Li7.2 La3 Zr1.8 Gd0.2 O12 |Li cells exhibit excellent cycling performance. Li7+x La3 Zr2-x Gdx O12 could be promising Li-ion solid electrolytes.