  In the last decade, a large number of studies at the experimental level in
electrochemical systems for energy storage devices have been performed.
However, theoretical approaches are highly desirable to understand the
physicochemical properties giving rise to energy storage phenomena. This work
was intended to provide insights into the $in$ $silico$ design of novel
nanocomposite materials formed by the Keggin polyoxometalate SiW12 anchored to
an organic functional group $\varphi-X$ (with $X = -NH2, -OH, -COH$ and
$-COOH$), linked to a carbon nanotube. In these systems, the Density of States
around the Fermi level is enhanced, giving the composite material the capacity
of facile electron transport that may be determinant at the charge/discharge
cycling performed in energy storage devices. Charge transfer at the composite
materials under study is greatest for the $\varphi-COOH$ functional group,
yielding an attraction with the SiW12 cluster of the same order of magnitude as
that of covalent nature. The rest of the functional groups induce a
non-covalent interaction of the electrostatic type, mediated by a van der Waals
attraction. Our proposed methodology may represent a tool to develop novel
electrode materials that may improve the performance on energy storage devices,
such as supercapacitors or Li$-$ion batteries.
