  ${\beta}$- Eucryptite (LiAlSiO4) is a potential electrolyte for Li- ion
battery due to its high Li- ion conductivity and very small volume thermal
expansion coefficient. We have performed ab-initio molecular dynamics
simulations of $\beta$- Eucryptite to study the origin of high temperature
superionic phase transition in this material. The simulations are able to
provide the microscopic understanding of the one -dimensional superionicity
that occurs along the hexagonal c-axis and is associated with the
order-disorder nature of the phase transition. The Li ionic conductivity is
found to enhance due to the anisotropic negative thermal expansion along
hexagonal c-axis. The introduction of defects in the crystal like, excess Li in
interstitial sites, Li vacancy and O vacancy are found to significantly
increase the ionic conductivity and hence might reduce the temperature of the
superionic phase transition in this material.
