Electrode Structures

Question 1

Why are electrodes 3D structures?

Answer 1

To increase the reaction area per volume to facilitate heterogenous electrochemical reactions

Question 2

List 4 additional benefits of 3D electrode structures

Answer 2

1) Storage volume for solid reactants
2) Support dispersed catalysts
3) Establishing a “three-phase boundary”
4) Efficiently evolving gases

Question 3

In a porous electrode, what is the ‘front’?

Answer 3

The edge of the electrode next to the electrolyte

Question 4

In a porous electrode, what is the ‘back’?

Answer 4

The edge of the electrode next to the current collector

Question 5

In a porous electrode, what is ‘porosity’?

Answer 5

The empty or void portion of the electrode available to the electrolyte

Question 6

In a porous electrode, what is the ‘superficial area’?

Answer 6

The area of a plane cutting through the electrode normal to the direction of superficial current

Question 7

In a porous electrode, what is the ‘specific interfacial area’?

Answer 7

The actual physical surface area of electrode in contact with the electrolyte divided by the volume of the electrode.

Question 8

How is pore size and specific interfacial area calculated in reality?

Answer 8

Using Hg-intrusion porosimetry

Question 9

What is tortuosity?

Answer 9

The effective transport properties for a porous media that relates to the bulk transport properties in the effective area

Question 10

What are the two effects impacting tortuosity?

Answer 10

1) increased path length
2) reduced cross-sectional area (due to solid phase)