Dual Substitution Strategy to Enhance Li+ Ionic Conductivity in Li7La3Zr2O12 Solid Electrolyte
| Autor: | Lucienne Buannic, B. Orayech, Frederic Aguesse, Javier Carrasco, William Manalastas, Juan Miguel López del Amo, John A. Kilner, Nebil A. Katcho, Wei Zhang, Anna Llordes |
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| Rok vydání: | 2017 |
| Předmět: |
Technology
Materials science General Chemical Engineering Materials Science Inorganic chemistry chemistry.chemical_element Materials Science Multidisciplinary SC-45 NMR 02 engineering and technology Electrolyte DIFFRACTION 010402 general chemistry Electrochemistry 01 natural sciences 09 Engineering Phase (matter) Materials Chemistry Fast ion conductor LITHIUM Ionic conductivity OXIDES Materials COORDINATION Science & Technology 1ST-PRINCIPLES STABILITY Dopant Chemistry Physical General Chemistry ALUMINUM 021001 nanoscience & nanotechnology 0104 chemical sciences Chemistry chemistry Chemical engineering Physical Sciences GARNET Lithium Charge carrier BATTERIES 03 Chemical Sciences 0210 nano-technology |
| Zdroj: | Chemistry of Materials. 29:1769-1778 |
| ISSN: | 1520-5002 0897-4756 |
| Popis: | Solid state electrolytes could address the current safety concerns of lithium-ion batteries as well as provide higher electrochemical stability and energy density. Among solid electrolyte contenders, garnet-structured Li7La3Zr2O12 appears as a particularly promising material owing to its wide electrochemical stability window; however, its ionic conductivity remains an order of magnitude below that of ubiquitous liquid electrolytes. Here, we present an innovative dual substitution strategy developed to enhance Li-ion mobility in garnet-structured solid electrolytes. A first dopant cation, Ga3+, is introduced on the Li sites to stabilize the fast-conducting cubic phase. Simultaneously, a second cation, Sc3+, is used to partially populate the Zr sites, which consequently increases the concentration of Li ions by charge compensation. This aliovalent dual substitution strategy allows fine-tuning of the number of charge carriers in the cubic Li7La3Zr2O12 according to the resulting stoichiometry, Li7–3x+yGaxLa3Zr2–yScyO12. The coexistence of Ga and Sc cations in the garnet structure is confirmed by a set of simulation and experimental techniques: DFT calculations, XRD, ICP, SEM, STEM, EDS, solid state NMR, and EIS. This thorough characterization highlights a particular cationic distribution in Li6.65Ga0.15La3Zr1.90Sc0.10O12, with preferential Ga3+ occupation of tetrahedral Li24d sites over the distorted octahedral Li96h sites. 7Li NMR reveals a heterogeneous distribution of Li charge carriers with distinct mobilities. This unique Li local structure has a beneficial effect on the transport properties of the garnet, enhancing the ionic conductivity and lowering the activation energy, with values of 1.8 × 10–3 S cm–1 at 300 K and 0.29 eV in the temperature range of 180 to 340 K, respectively. |
| Databáze: | OpenAIRE |
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