  We consider the one-dimensional symmetric simple exclusion process with a
slow bond. In this model, whilst all the transition rates are equal to one, a
particular bond, the \emph{slow bond}, has associated transition rate of value
$N^{-1}$, where $N$ is the scaling parameter. This model has been considered in
previous works on the subject of hydrodynamic limit and fluctuations. In this
paper, assuming uniqueness for weak solutions of hydrodynamic equation
associated to the perturbed process, we obtain dynamical large deviations
estimates in the diffusive scaling. The main challenge here is the fact that
the presence of the slow bond gives rise to Robin's boundary conditions in the
\emph{continuum}, substantially complicating the large deviations scenario.
