%0 Journal Article
%A Lei Cheng
%A Miao Liu
%A Apurva Mehta
%A Huolin L Xin
%A Feng Lin
%A Kristin A Persson
%A Guoying Chen
%A Ethan J Crumlin
%A Marca M Doeff
%B ACS Applied Energy Materials
%D 2018
%G eng
%N 12
%P 7244 - 7252
%R 10.1021/acsaem.8b01723
%T Garnet Electrolyte Surface Degradation and Recovery
%V 1
%8 11/2018
%! ACS Appl. Energy Mater.
%X <p><span>Ceramic materials based on the garnet structure 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) show great promise as lithium-ion conducting electrolytes for solid-state lithium batteries. However, these materials exhibit surface degradation when exposed to air and moisture, which adversely impacts their functioning in operating devices. In this work, we use several depth-profiling and in situ techniques to probe the nature of the surface reactions that occur when aluminum (Al)-substituted LLZO is exposed to air. These experiments show that a proton exchange reaction occurs near the surface of the LLZO and leads to change in its chemistry and structure, concomitant with the formation of Li</span><span>2</span><span>CO</span><span>3</span><span>. But these reactions can be readily reversed by heating samples at 250 °C under an inert atmosphere to recover LLZO surface chemistry and structure. Symmetrical cells containing samples treated this way exhibited much lower area specific impedances than those containing air-exposed LLZO without the treatment, confirming the reversal of the degradation process. Our results show a process to rejuvenate LLZO surface, and this opens the possibility of integrating this material in solid-state devices.</span></p>