Gallium-Doped Li7La3Zr2O12 Garnet-Type Electrolytes with High Lithium-Ion Conductivity

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• 作者：Jian-Fang Wu ; En-Yi Chen ; Yao Yu ; Lin Liu ; Yue Wu ; Wei Kong Pang ; Vanessa K. Peterson ; Xin Guo
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2017
• 出版时间：January 18, 2017
• 年：2017
• 卷：9
• 期：2
• 页码：1542-1552
• 全文大小：772K
• ISSN：1944-8252

文摘

Owing to their high conductivity, crystalline Li_7–3<i>xi>Ga_<i>xi>La₃Zr₂O₁₂ garnets are promising electrolytes for all-solid-state lithium-ion batteries. Herein, the influence of Ga doping on the phase, lithium-ion distribution, and conductivity of Li_7–3<i>xi>Ga_<i>xi>La₃Zr₂O₁₂ garnets is investigated, with the determined concentration and mobility of lithium ions shedding light on the origin of the high conductivity of Li_7–3<i>xi>Ga_<i>xi>La₃Zr₂O₁₂. When the Ga concentration exceeds 0.20 Ga per formula unit, the garnet-type material is found to assume a cubic structure, but lower Ga concentrations result in the coexistence of cubic and tetragonal phases. Most lithium within Li_7–3<i>xi>Ga_<i>xi>La₃Zr₂O₁₂ is found to reside at the octahedral 96<i>hi> site, away from the central octahedral 48<i>gi> site, while the remaining lithium resides at the tetrahedral 24<i>di> site. Such kind of lithium distribution leads to high lithium-ion mobility, which is the origin of the high conductivity; the highest lithium-ion conductivity of 1.46 mS/cm at 25 °C is found to be achieved for Li_7–3<i>xi>Ga_<i>xi>La₃Zr₂O₁₂ at <i>xi> = 0.25. Additionally, there are two lithium-ion migration pathways in the Li_7–3<i>xi>Ga_<i>xi>La₃Zr₂O₁₂ garnets: 96<i>hi>-96<i>hi> and 24<i>di>-96<i>hi>-24<i>di>, but the lithium ions transporting through the 96<i>hi>-96<i>hi> pathway determine the overall conductivity.