Origin
of Outstanding Stability in the Lithium Solid Electrolyte Materials:
Insights from Thermodynamic Analyses Based on First-Principles Calculations
- Publication date
- Publisher
Abstract
First-principles calculations were
performed to investigate the electrochemical stability of lithium
solid electrolyte materials in all-solid-state Li-ion batteries. The
common solid electrolytes were found to have a limited electrochemical
window. Our results suggest that the outstanding stability of the
solid electrolyte materials is not thermodynamically intrinsic but
is originated from kinetic stabilizations. The sluggish kinetics of
the decomposition reactions cause a high overpotential leading to
a nominally wide electrochemical window observed in many experiments.
The decomposition products, similar to the solid-electrolyte-interphases,
mitigate the extreme chemical potential from the electrodes and protect
the solid electrolyte from further decompositions. With the aid of
the first-principles calculations, we revealed the passivation mechanism
of these decomposition interphases and quantified the extensions of
the electrochemical window from the interphases. We also found that
the artificial coating layers applied at the solid electrolyte and
electrode interfaces have a similar effect of passivating the solid
electrolyte. Our newly gained understanding provided general principles
for developing solid electrolyte materials with enhanced stability
and for engineering interfaces in all-solid-state Li-ion batteries