Towards first principles modeling of electrochemical electrode–electrolyte interfaces

Nielsen, Michael Havbro Faber; Björketun, Mårten E.; Hansen, Martin Hangaard; Rossmeisl, Jan

doi:10.1016/j.susc.2014.08.018

Cited by 84 publications

(89 citation statements)

References 21 publications

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“…1f should not be a candidate for equilibrium interfaces, 68 at least under these UHV conditions. If a liquid electrolyte is present, it cannot be ruled out that Li + vacancy near the outer surface may be stabilized; we speculate that this could even yield a multitude of equilibrium Li + configurations in Li-containing films, and therefore more than one PZC at different voltages.…”

Section: B Lithium Metal Cohesive Energy (V I ) For Voltagementioning

confidence: 99%

How Voltage Drops Are Manifested by Lithium Ion Configurations at Interfaces and in Thin Films on Battery Electrodes

Leung

Leenheer

2015

J. Phys. Chem. C

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Battery electrode surfaces are generally coated with electronically insulating solid films of thickness 1-50 nm. Both electrons and Li + can move at the electrode-surface film interface in response to the voltage, which adds complexity to the "electric double layer" (EDL). We apply Density Functional Theory (DFT) to investigate how the applied voltage is manifested as changes in the EDL at atomic lengthscales, including charge separation and interfacial dipole moments. Illustrating examples include Li 3 PO 4 , Li 2 CO 3 , and Li x Mn 2 O 4 thin-films on Au(111) surfaces under ultrahigh vacuum conditions. Adsorbed organic solvent molecules can strongly reduce voltages predicted in vacuum. We propose that manipulating surface dipoles, seldom discussed in battery studies, may be a viable strategy to improve electrode passivation. We also distinguish the computed potential governing electrons, which is the actual or instantaneous voltage, and the "lithium cohesive energy"-based voltage governing Li content widely reported in DFT calculations, which is a slower-responding self-consistency criterion at interfaces. This distinction is critical for a comprehensive description of electrochemical activities on electrode surfaces, including Li + insertion dynamics, parasitic electrolyte decomposition, and electrodeposition at overpotentials. keywords: lithium ion batteries; voltage prediction; density functional theory; computational electrochemistry

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Section: B Lithium Metal Cohesive Energy (V I ) For Voltagementioning

confidence: 99%

How Voltage Drops Are Manifested by Lithium Ion Configurations at Interfaces and in Thin Films on Battery Electrodes

Leung

Leenheer

2015

J. Phys. Chem. C

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“…In recent years, several approaches have been developed to address the issue of constant electrode potential [1][2][3][4][5][6][7][8], a prerequisite to study electrochemical reactions. These approaches are thermodynamically open with respect to electrons, but canonical with respect to protons, as pointed out by Rossmeisl and co-workers [9]. For example, enforcing a specific pH value would require an exchange of protons with a chemical reservoir.…”

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confidence: 99%

First-Principles Approach to Model Electrochemical Reactions: Understanding the Fundamental Mechanisms behind Mg Corrosion

et al. 2018

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Combining concepts of semiconductor physics and corrosion science, we develop a novel approach that allows us to perform ab initio calculations under controlled potentiostat conditions for electrochemical systems. The proposed approach can be straightforwardly applied in standard density functional theory codes. To demonstrate the performance and the opportunities opened by this approach, we study the chemical reactions that take place during initial corrosion at the water-Mg interface under anodic polarization. Based on this insight, we derive an atomistic model that explains the origin of the anodic hydrogen evolution.

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“…Likewise, one needs extra measures of caution when computationally assessing the electrochemical stability of an electrolyte. Currently, the AIMD approach suffers from unrealistic configurations of the interfaces due to the limited number of solvent molecules explicitly included in calculations which leads to ambiguity in the definition of the electrode potential, 12 insufficient accounting for the dielectric response of the liquid environment, [13][14][15][16] erroneous assessments of the potential of zero charge (PZC), 15,17,[18][19][20][21][22] the spatial profile of the average electrostatic potential in the EDL and its capacitance. Moreover, in practically realizable unit cells for AIMD even an elementary fluctuation of the ion distribution or polar solvent molecules near the interface, caused by either thermal motion or by the loss of inventory accompanying reduction, causes a drastic change, on the order of ±1.0 V, in the calculated electrode potential.…”

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confidence: 99%

Improving Continuum Models to Define Practical Limits for Molecular Models of Electrified Interfaces

Baskin

2017

J. Electrochem. Soc.

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We develop a continuum theory of electrolyte solutions in contact with a metal electrode, based on a generalized free energy functional, and use it to explore the structure of the electric double layer at different electrochemical conditions. The model captures the effects of specific adsorption of ions and solvent polarization, and can be applied on the same footing to cases with non-zero faradaic current, beyond the classical double-layer regime. These advances permit the prediction of peculiar character in the ion profiles at electrode potentials near the redox level, exploration of the electrochemical stability of the interface, and differentiation between the mechanisms of electron and ion transport and associated time scales. The developed methodology enables us to selfconsistently determine the fundamental limits for a microscopic description of biased interfaces, in terms characteristic sizes and time scales of relevant processes, within atomistic and ab initio molecular dynamics simulations. As the efficiency of electrochemical conversion is dictated by the energetics of elementary charge transfer reactions occurring at the electrode/electrolyte interface, the formulation of methods of control over these reactions has become the pivotal goal of fundamental material science for advanced energy storage systems. The ultimate goal of theoretical electrochemistry then is to explore the energetics of the relevant processes from an atomistic perspective by means of ab initio molecular dynamics (AIMD) where ionic and electronic components of the system are described explicitly and are constrained by various realistic conditions, such as the external bias, the temperature and the electrolyte concentration. However, despite more than a decade of efforts this goal is still far from being fulfilled.There are several interconnected fundamental problems to resolve before an atomistic approach could be routinely used to describe electrochemistry, if only at the level of a half-cell (i.e., a single electrodeelectrolyte interface). First, there are at least three distinct regimes of performance of the electrochemical interface and each of these is characterized by different sets of the time and space scales: a) the classical electric double layer (EDL) regime when no charge transfer is assumed, b) the regime of an electrode at equilibrium with the electrolyte (open circuit conditions, (OCP)) when only an exchange current in a form of mutually compensating fluxes of charged particles is possible, and c) the "true" electrochemical regime with a non-zero net faradaic current. As long as the goal of atomistic simulations is to reach a state when one would observe the actual electrochemical reactions driven by the bias, the computational electrode potential scanning protocol should carry the system through a set of (quasi-)equilibrium points at which the atomistic structure is consistent with the targeted external conditions. The key requirement for such simulations is thus thermodynamic stability of the interface that encom...

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Towards first principles modeling of electrochemical electrode–electrolyte interfaces

Cited by 84 publications

References 21 publications

How Voltage Drops Are Manifested by Lithium Ion Configurations at Interfaces and in Thin Films on Battery Electrodes

How Voltage Drops Are Manifested by Lithium Ion Configurations at Interfaces and in Thin Films on Battery Electrodes

First-Principles Approach to Model Electrochemical Reactions: Understanding the Fundamental Mechanisms behind Mg Corrosion

Improving Continuum Models to Define Practical Limits for Molecular Models of Electrified Interfaces

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