  The extreme pressures required to stabilize the recently discovered
superhydrides represent a major obstacle to their practical application. In
this paper, we propose a novel route to attain high-temperature
superconductivity in hydrides at ambient pressure, by doping commercial metal
borohydrides. Using first-principles calculations based on Density Functional
Theory and Migdal-Eliashberg theory, we demonstrate that in Ca(BH$_4$)$_2$ a
moderate hole doping of 0.03 holes per formula unit, obtained through a partial
replacement of Ca with monovalent K, is sufficient to achieve $T_c$'s as high
as 110 K. The high-$T_c$ arises because of the strong electron-phonon coupling
between the B-H $\sigma$ molecular orbitals and bond-stretching phonons. Using
a random sampling of large supercells to estimate the local effects of doping,
we show that the required doping can be achieved without significant disruption
of the electronic structure and at moderate energetic cost. Given the wide
commercial availability of metal borohydrides, the ideas presented here can
find prompt experimental confirmation. If successful, the synthesis of
high-$T_c$ doped borohydrides will represent a formidable advancement towards
technological exploitation of conventional superconductors.
