1 research outputs found
Forced Disorder in the Solid Solution Li<sub>3</sub>P–Li<sub>2</sub>S: A New Class of Fully Reduced Solid Electrolytes for Lithium Metal Anodes
All-solid-state batteries based on non-combustible solid
electrolytes
are promising candidates for safe energy storage systems. In addition,
they offer the opportunity to utilize metallic lithium as an anode.
However, it has proven to be a challenge to design an electrolyte
that combines high ionic conductivity and processability with thermodynamic
stability toward lithium. Herein, we report a new highly conducting
solid solution that offers a route to overcome these challenges. The
Li–P–S ternary was first explored via a combination
of high-throughput crystal structure predictions and solid-state synthesis
(via ball milling) of the most promising compositions, specifically,
phases within the Li3P–Li2S tie line.
We systematically characterized the structural properties and Li-ion
mobility of the resulting materials by X-ray and neutron diffraction,
solid-state nuclear magnetic resonance spectroscopy (relaxometry),
and electrochemical impedance spectroscopy. A Li3P–Li2S metastable solid solution was identified, with the phases
adopting the fluorite (Li2S) structure with P substituting
for S and the extra Li+ ions occupying the octahedral voids
and contributing to the ionic transport. The analysis of the experimental
data is supported by extensive quantum-chemical calculations of both
structural stability, diffusivity, and activation barriers for Li+ transport. The new solid electrolytes show Li-ion conductivities
in the range of established materials, while their composition guarantees
thermodynamic stability toward lithium metal anodes