Electrochemistry from first-principles in the grand canonical ensemble

Publication date
2021-07-12
Document type
Research article
Author
Bhandari, Arihant
Peng, Chao
Dziedzic, Jacek
Anton, Lucian
Owen, John R.
Skylaris, Chris-Kriton
Organisational unit
DOI
URI
ISSN
Series or journal
The journal of chemical physics : JCP
Periodical volume
155
Periodical issue
2
Peer-reviewed
✅
Part of the university bibliography
✅
Abstract
Progress in electrochemical technologies, such as automotive batteries, supercapacitors, and fuel cells, depends greatly on developing improved charged interfaces between electrodes and electrolytes. The rational development of such interfaces can benefit from the atomistic understanding of the materials involved by first-principles quantum mechanical simulations with Density Functional Theory (DFT). However, such simulations are typically performed on the electrode surface in the absence of its electrolyte environment and at constant charge. We have developed a new hybrid computational method combining DFT and the Poisson-Boltzmann equation (P-BE) capable of simulating experimental electrochemistry under potential control in the presence of a solvent and an electrolyte. The charged electrode is represented quantum-mechanically via linear-scaling DFT, which can model nanoscale systems with thousands of atoms and is neutralized by a counter electrolyte charge via the solution of a modified P-BE. Our approach works with the total free energy of the combined multiscale system in a grand canonical ensemble of electrons subject to a constant electrochemical potential. It is calibrated with respect to the reduction potential of common reference electrodes, such as the standard hydrogen electrode and the Li metal electrode, which is used as a reference electrode in Li-ion batteries. Our new method can be used to predict electrochemical properties under constant potential, and we demonstrate this in exemplar simulations of the differential capacitance of few-layer graphene electrodes and the charging of a graphene electrode coupled to a Li metal electrode at different voltages.
Description
Funding Information: This work was carried out with funding from the Faraday Institution (faraday.ac.uk; EP/S003053/1), Grant No. FIRG003. The majority of computations presented in this work were performed on the Iridis 5 supercomputer of the University of Southampton and the Michael supercomputer of the Faraday Institution. We acknowledge the United Kingdom Materials and Molecular Modeling Hub for computational resources, partially funded by the EPSRC (Grant Nos. EP/P020194/1 and EP/T022213/1).
Publisher Copyright: {\textcopyright} 2021 Author(s). Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
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