Chapter 4
Electrode reactions
Course notes
Thermodynamics and electrochemical kinetics
4.1 – Electrode thermodynamics
4.1.1 – Electrode
An electrode is a system made up of an electronic or mixed conductor (metal
or electrode material) in contact with a solid electrolyte and is host to one or
several oxidation-reduction reactions.
4.1.2 – Electrode potential
The electrode potential is the electrical potential of an electrode measured
with respect to a reference electrode or other comparative electrode. With zero
current, it is called the open-circuit potential E i=0 . When the electrode is host
to a single electrochemical reaction in equilibrium,
Ox + ne m Red
the open-circuit potential E th is given by the Nernst equation
[
]
[ ]
ln
E
E
n F
RT
Red
Ox
/
th
Ox Red
e
e
=
+
°
by associating the activities of the various species to their concentrations [Ox] e
and [Red] e . E th is treated as a thermodynamic or theoretical potential. The
standard potential E ° Ox/Red depends on the two species involved in the reaction.
© Springer Nature Switzerland AG 2020
A. Hammou and S. Georges, Solid-State Electrochemistry,
https://doi.org/10.1007/978-3-030-39659-6_4
171