%0 Journal Article
%A Daniel Rettenwander
%A Reinhard Wagner
%A Andreas Reyer
%A Maximilian Bonta
%A Lei Cheng
%A Marca M Doeff
%A Andreas Limbeck
%A Martin Wilkening
%A Georg Amthauer
%B The Journal of Physical Chemistry C
%D 2018
%G eng
%N 7
%P 3780 - 3785
%R 10.1021/acs.jpcc.7b12387
%T Interface Instability of Fe-Stabilized Li<sub>7</sub>La <sub>3</sub>Zr<sub>2</sub>O<sub>12</sub> versus Li Metal
%V 122
%8 01/2018
%! J. Phys. Chem. C
%X <p><span>he interface stability versus Li represents a major challenge in the development of next-generation all-solid-state batteries (ASSB), which take advantage of the inherently safe ceramic electrolytes. Cubic Li</span><span>7</span><span>La</span><span>3</span><span>Zr</span><span>2</span><span>O</span><span>12</span><span>&nbsp;garnets represent the most promising electrolytes for this technology. The high interfacial impedance versus Li is, however, still a bottleneck toward future devices. Herein, we studied the electrochemical performance of Fe</span><span>3+</span><span>-stabilized Li</span><span>7</span><span>La</span><span>3</span><span>Zr</span><span>2</span><span>O</span><span>12</span><span>&nbsp;(LLZO:Fe) versus Li metal and found a very high total conductivity of 1.1 mS cm</span><span>–1</span><span>&nbsp;at room temperature but a very high area specific resistance of ∼1 kΩ cm</span><span>2</span><span>. After removing the Li metal electrode we observe a black surface coloration at the interface, which clearly indicates interfacial degradation. Raman- and nanosecond laser-induced breakdown spectroscopy reveals, thereafter, the formation of a 130 μm thick tetragonal LLZO interlayer and a significant Li deficiency of about 1–2 formula units toward the interface. This shows that cubic LLZO:Fe is not stable versus Li metal by forming a thick tetragonal LLZO interlayer causing high interfacial impedance.</span></p>