  The development of silicon anodes to replace conventional graphite in efforts
to increase energy densities of lithium-ion batteries has been largely impeded
by poor interfacial stability against liquid electrolytes. Here, stable
operation of 99.9 weight% micro-Si (uSi) anode is enabled by utilizing the
interface passivating properties of sulfide based solid-electrolytes. Bulk to
surface characterization, as well as quantification of interfacial components
showed that such an approach eliminates continuous interfacial growth and
irreversible lithium losses. In uSi || layered-oxide full cells, high current
densities at room temperature (5 mA cm 2), wide operating temperature
(-20{\deg}C to 80{\deg}C) and high loadings (>11 mAh cm-2) were demonstrated
for both charge and discharge operations. The promising battery performance can
be attributed to both the desirable interfacial property between uSi and
sulfide electrolytes, as well as the unique chemo-mechanical behavior of the
Li-Si alloys.
