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Title: Role of Dynamically Frustrated Bond Disorder in a Li + Superionic Solid Electrolyte

Inorganic lithium solid electrolytes are critical components in next-generation solid-state batteries, yet the fundamental nature of the cation-anion interactions and their relevance for ionic conductivity in these materials remains enigmatic. Here, we employ first-principles molecular dynamics simulations to explore the interplay between chemistry, structure, and functionality of a highly conductive Li + solid electrolyte, Li3InBr6. Using local-orbital projections to dynamically track the evolution of the electronic charge density, the simulations reveal rapid, correlated fluctuations between cation-anion interactions with different degrees of directional covalent character. These chemical bond dynamics are shown to correlate with Li + mobility, and are enabled thermally by intrinsic frustration between the preferred geometries of chemical bonding and lattice symmetry. We suggest that the fluctuating chemical environment from the polarizable anions functions similar to a solvent, contributing to the superionic behavior of Li 3InBr 6 by temporarily stabilizing configurations favorable for migrating Li +. The generality of these conclusions for understanding solid electrolytes and key factors governing the superionic phase transition is discussed.
Authors:
 [1] ;  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-684599
Journal ID: ISSN 0897-4756; TRN: US1702929
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 28; Journal Issue: 20; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 25 ENERGY STORAGE
OSTI Identifier:
1408073