Functional Materials for Energy
Decoding the Resistivity of Solid Electrolytes for Batteries April 02, 2014
The atomic-scale structure of a typical GB in LLTO is shown in false color. The atomic structure and chemical distributions within the property-controlling GBs are schematically presented.
The atomic-scale origin of grain-boundary (GB) resistance in solid electrolytes has been revealed by electron microscopy and spectroscopy. Inorganic solid electrolytes have the potential for enabling intrinsically safe, energy-dense batteries. However, to date these materials have demonstrated only limited success due to demonstrated high resistance across grains, or small crystallites, in the electrolyte material. This resistance across the GB lowers the total conductivity by several orders of magnitude. For the first time, the microscopic origin of such high GB resistivity in the prototype solid electrolyte (Li3xLa2/3-x)TiO3 (LLTO) has been observed. Sub-Å-resolution electron microscopy and spectroscopy revealed that the LLTO GBs exhibit a severe structural and chemical modification, resulting in a Ti-O binary compound thin film with a 2-3 unit cell thickness. Such a GB structure is not energetically favorable for either Li accommodation or transport, resulting in the poor GB conductivity. The present study elucidates the structural and chemical basis for the large grain-boundary resistance in Li superionic conductors and paves the way for the design of future solid electrolytes with superior performance.
C. Ma, K. Chen, C. Liang, C.-W. Nan, R. Ishikawa, K. More and M. Chi, “Atomic-scale origin of the large grain-boundary resistance in perovskite Li-ion-conducting solid electrolytes,” Energy & Environmental Science DOI: 10.1039/c4ee00382a.
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