  We predict the existence of large barocaloric effects above room temperature
in the thermoelectric fast-ion conductor Cu$_{2}$Se by using classical
molecular dynamics simulations and first-principles computational methods. A
hydrostatic pressure of $1$ GPa induces large isothermal entropy changes of
$|\Delta S| \sim 15$-$45$ Jkg$^{-1}$K$^{-1}$ and adiabatic temperature shifts
of $|\Delta T| \sim 10$ K in the temperature interval $400 \le T \le 700$ K.
Structural phase transitions are absent in the analysed thermodynamic range.
The causes of such large barocaloric effects are significant $P$-induced
variations on the ionic conductivity of Cu$_{2}$Se and the inherently high
anharmonicity of the material. Uniaxial stresses of the same magnitude, either
compressive or tensile, produce comparatively much smaller caloric effects,
namely, $|\Delta S| \sim 1$ Jkg$^{-1}$K$^{-1}$ and $|\Delta T| \sim 0.1$ K, due
to practically null influence on the ionic diffusivity of Cu$_{2}$Se. Our
simulation work shows that thermoelectric compounds presenting high ionic
disorder, like copper and silver-based chalcogenides, may render large
mechanocaloric effects and thus are promising materials for engineering
solid-state cooling applications that do not require the application of
electric fields.
