posted on 2017-12-18, 00:00authored byShaofei Wang, Henghui Xu, Wangda Li, Andrei Dolocan, Arumugam Manthiram
Benefiting
from extremely high shear modulus and high ionic transference
number, solid electrolytes are promising candidates to address both
the dendrite-growth and electrolyte-consumption problems inherent
to the widely adopted liquid-phase electrolyte batteries. However,
solid electrolyte/electrode interfaces present high resistance and
complicated morphology, hampering the development of solid-state battery
systems, while requiring advanced analysis for rational improvement.
Here, we employ an ultrasensitive three-dimensional (3D) chemical
analysis to uncover the dynamic formation of interphases at the solid
electrolyte/electrode interface. While the formation of interphases
widens the electrochemical window, their electronic and ionic conductivities
determine the electrochemical performance and have a large influence
on dendrite growth. Our results suggest that, contrary to the general
understanding, highly stable solid electrolytes with metal anodes
in fact promote fast dendritic formation, as a result of less Li consumption
and much larger curvature of dendrite tips that leads to an enhanced
electric driving force. Detailed thermodynamic analysis shows an interphase
with low electronic conductivity, high ionic conductivity, and chemical
stability, yet having a dynamic thickness and uniform coverage is
needed to prevent dendrite growth. This work provides a paradigm for
interphase design to address the dendrite challenge, paving the way
for the development of robust, fully operational solid-state batteries.