  Earth's inner core (IC) serves as a reservoir for volatile elements, which
significantly affects its behavior and properties. Recent studies suggest that
superionicity can be observed in ice and iron hydrides under high-pressure and
temperature conditions, providing an alternative understanding of the planet's
interior. In this study, we demonstrated that electride formation drives the
superionic state in iron hydride under IC pressure conditions. The electride
stabilizes the iron lattice and provides a pathway for volatile diffusion. The
coupling between lattice stability and superionicity is triggered near 100 GPa
and enhanced at higher pressures. The electride-driven superionicity can also
be generalized for volatiles in other rocky planetary cores. These findings
provide new insights into the mechanisms of core formation and evolution of
rocky planets.
