  Ionic conductivity in solid electrolytes is commonly expected to exhibit
Arrhenius dependence on temperature, determined by a well-defined activation
energy. Consequently, a standard approach involves calculating this energy
using quasi-static methods and using the Arrhenius form to extrapolate the
numerical results from one temperature range to another. Despite the ubiquity
of this Arrhenius-based modeling, disagreements frequently arise between theory
and experiment, and even between different theoretical studies. By considering
a tractable minimal model, we elucidate the reason behind the breakdown of the
Arrhenius conductivity form. This breakdown is driven by non-trivial
phase-space boundaries between conducting and non-conducting regimes, and
depends on the kinetic properties of the system.
