cm7b03002_si_001.pdf (620.25 kB)
Surface Chemistry Mechanism of Ultra-Low Interfacial Resistance in the Solid-State Electrolyte Li7La3Zr2O12
journal contribution
posted on 2017-09-01, 00:00 authored by Asma Sharafi, Eric Kazyak, Andrew L. Davis, Seungho Yu, Travis Thompson, Donald J. Siegel, Neil P. Dasgupta, Jeff SakamotoThe
impact of surface chemistry on the interfacial resistance between
the Li7La3Zr2O12 (LLZO)
solid-state electrolyte and a metallic Li electrode is revealed. Control
of surface chemistry allows the interfacial resistance to be reduced
to 2 Ω cm2, lower than that of liquid electrolytes,
without the need for interlayer coatings. A mechanistic understanding
of the origins of ultra-low resistance is provided by quantitatively
evaluating the linkages between interfacial chemistry, Li wettability,
and electrochemical phenomena. A combination of Li contact angle measurements,
X-ray photoelectron spectroscopy (XPS), first-principles calculations,
and impedance spectroscopy demonstrates that the presence of common
LLZO surface contaminants, Li2CO3 and LiOH,
result in poor wettability by Li and high interfacial resistance.
On the basis of this mechanism, a simple procedure for removing these
surface layers is demonstrated, which results in a dramatic increase
in Li wetting and the elimination of nearly all interfacial resistance.
The low interfacial resistance is maintained over one-hundred cycles
and suggests a straightforward pathway to achieving high energy and
power density solid-state batteries.