TY - JOUR
T1 - Enhancing Li ion conductivity of garnet-type Li 5La 3Nb 2O 12 by Y- and Li-codoping
T2 - Synthesis, structure, chemical stability, and transport properties
AU - Narayanan, Sumaletha
AU - Ramezanipour, Farshid
AU - Thangadurai, Venkataraman
PY - 2012/9/27
Y1 - 2012/9/27
N2 - Novel Li-stuffed garnet-like "Li 5+2xLa 3Nb 2-xY xO 12" (0.05 ≤ x ≤ 0.75) was prepared via solid-state reaction in air and characterized using ex situ and in situ powder X-ray diffraction (PXRD), 7Li and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR), scanning electron microscopy (SEM), thermo-gravimetric analysis (TGA), and AC impedance spectroscopy. Rietveld refinement with the PXRD data confirmed the formation of a cubic, garnet-like Ia-3d structure. 7Li MAS NMR showed a single sharp peak close to 0 ppm as the usual trend for fast Li ion conducting garnets. Among the materials studied, "Li 6.5La 3Nb 1.25Y 0.75O 12" showed a very high bulk ionic conductivity of 2.7 × 10 -4 S cm -1 at 25 °C, which is the highest value found in garnet-type compounds, and is only reported for Li 7La 3Zr 2O 12. The in situ PXRD measurements revealed structural stability up to 400-600 °C after water treatment as well as chemical compatibility with high voltage Li cathodes Li 2MMn 3O 8 (M = Co, Fe). The current work demonstrates that slight Al contamination from the Al 2O 3 crucible, which is commonly observed in this class of materials and was detected by 27Al MAS NMR, does not affect the Li ionic conductivity and chemical stability of "Li 5+2xLa 3Nb 2-xY xO 12" garnets. It also shows that Li stuffing is critical to improve further the ionic conductivity of parent compound Li 5La 3Nb 2O 12. Y 3+ seems to be a very efficient dopant to improve the ionic conductivity of garnets compared to other investigated dopants that include M 2+ (M = alkaline earth metals), In 3+, and Zr 4+.
AB - Novel Li-stuffed garnet-like "Li 5+2xLa 3Nb 2-xY xO 12" (0.05 ≤ x ≤ 0.75) was prepared via solid-state reaction in air and characterized using ex situ and in situ powder X-ray diffraction (PXRD), 7Li and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR), scanning electron microscopy (SEM), thermo-gravimetric analysis (TGA), and AC impedance spectroscopy. Rietveld refinement with the PXRD data confirmed the formation of a cubic, garnet-like Ia-3d structure. 7Li MAS NMR showed a single sharp peak close to 0 ppm as the usual trend for fast Li ion conducting garnets. Among the materials studied, "Li 6.5La 3Nb 1.25Y 0.75O 12" showed a very high bulk ionic conductivity of 2.7 × 10 -4 S cm -1 at 25 °C, which is the highest value found in garnet-type compounds, and is only reported for Li 7La 3Zr 2O 12. The in situ PXRD measurements revealed structural stability up to 400-600 °C after water treatment as well as chemical compatibility with high voltage Li cathodes Li 2MMn 3O 8 (M = Co, Fe). The current work demonstrates that slight Al contamination from the Al 2O 3 crucible, which is commonly observed in this class of materials and was detected by 27Al MAS NMR, does not affect the Li ionic conductivity and chemical stability of "Li 5+2xLa 3Nb 2-xY xO 12" garnets. It also shows that Li stuffing is critical to improve further the ionic conductivity of parent compound Li 5La 3Nb 2O 12. Y 3+ seems to be a very efficient dopant to improve the ionic conductivity of garnets compared to other investigated dopants that include M 2+ (M = alkaline earth metals), In 3+, and Zr 4+.
U2 - 10.1021/jp304737x
DO - 10.1021/jp304737x
M3 - Article
AN - SCOPUS:84866865786
SN - 1932-7447
VL - 116
SP - 20154
EP - 20162
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 38
ER -