  Biredox ionic liquids are a new class of functionalized electrolytes that may
play an important role in future capacitive energy storage devices. By allowing
additional storage of electrons inside the liquids, they can improve device
performance significantly. However current devices employ nanoporous carbons in
which the diffusion of the liquid and the adsorption of the ions could be
affected by the occurrence of electron-transfer reactions. It is therefore
necessary to understand better the thermodynamics and the kinetics of such
reactions in biredox ionic liquids. Here we perform ab initio molecular
dynamics simulations of both the oxidized and reduced species of several
redox-active ionic molecules (used in biredox ionic liquids) dissolved in
acetonitrile solvent and compare them with the bare redox molecules. We show
that in all the cases, it is necessary to introduce a two Gaussian state model
to calculate the reaction free energies accurately. These reaction free
energies are only slightly affected by the presence of the IL group on the
molecule. We characterize the structure of the solvation shell around the redox
active part of the molecules and show that in the case of TEMPO-based molecules
strong reorientation effects occur during the oxidation reaction.
