2 research outputs found
Surface Chemistry Mechanism of Ultra-Low Interfacial Resistance in the Solid-State Electrolyte Li<sub>7</sub>La<sub>3</sub>Zr<sub>2</sub>O<sub>12</sub>
The
impact of surface chemistry on the interfacial resistance between
the Li<sub>7</sub>La<sub>3</sub>Zr<sub>2</sub>O<sub>12</sub> (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 cm<sup>2</sup>, 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, Li<sub>2</sub>CO<sub>3</sub> 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