Electrified electrode-electrolyte interfaces from first principles

Reactions occurring at the electrochemical interfaces under applied potential govern the functioning and performance of devices for energy conversion and storage. To describe this phenomena at the atomic scale, we have developed a method for performing density functional theory (DFT) calculations in a grand canonical ensemble under potential control [J. Chem. Phys., 2021, 155, 024114]. The charge developed on the electrode is neutralized by a build up of counter charge in the electrolyte, which is represented via Poisson-Boltzmann theory in a grand canonical ensemble [J. Chem. Phys., 2020, 153, 124101]. The method works in both fully periodic and open boundary conditions [J. Phys. Chem. C, 2020, 124, 7860], and has been implemented in the ONETEP program [J. Chem. Phys., 2020, 152, 174111] which has a linear-scaling computational cost with the number of atoms. The model parameters have been calibrated with respect to reduction potential of standard electrodes and activity coefficient of electrolytes. The model has been applied to study the differential capacitance of graphene based electrodes in supercapacitor applications, and lithium nucleation on graphite anode in Li-ion batteries [J. Mater. Chem. A, 2022, 10, 11426]. The predictions from the model agree well with experiments.