Issue 20, 2022

Non-equilibrium thermodynamics of mixed ionic-electronic conductive electrodes and their interfaces: a Ni/CGO study

Abstract

Non-equilibrium thermodynamics describe the current–voltage characteristics of electrochemical devices. For conventional electrode–electrolyte interfaces, the local activation overpotential is used to describe the electrostatic potential step between the two materials as a current is generated. However, the activation overpotential for the metal/mixed ionic-electronic conducting (MIEC) composite electrodes studied in this work originates at the MIEC–gas interface. Moreover, we have studied the effects of non-equilibrium on the electrostatic surface potential and evaluated its influence over electrode kinetics. By investigating two phase (2PB) and three phase boundary (3PB) reactions at the Ni/Ce1−xGdxO2−δ (Ni/CGO) electrode, we have demonstrated that the driving force for coupled ion-electron transfer is held at the CGO–gas interface for both reaction pathways. We also determined that the rate of coupled ion-electron transfer via the 3PB scales with the availability of free sites on the metallic surface, revealing a Sabatier-like relationship with regards to the selection of metallic phases. Finally, we demonstrated how the theory of the electrostatic surface potential can be applied to other systems outside of the well-studied H2/H2O electrode environment. These findings therefore provide an insight into the design of future electrode structures for a range of electrochemical devices.

Graphical abstract: Non-equilibrium thermodynamics of mixed ionic-electronic conductive electrodes and their interfaces: a Ni/CGO study

Supplementary files

Article information

Article type
Paper
Submitted
27 8 2021
Accepted
16 4 2022
First published
19 4 2022
This article is Open Access
Creative Commons BY license

J. Mater. Chem. A, 2022,10, 11121-11130

Non-equilibrium thermodynamics of mixed ionic-electronic conductive electrodes and their interfaces: a Ni/CGO study

N. J. Williams, I. D. Seymour, R. T. Leah, A. Banerjee, S. Mukerjee and S. J. Skinner, J. Mater. Chem. A, 2022, 10, 11121 DOI: 10.1039/D1TA07351F

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