Electro-osmotic flow and the limiting current in alkaline water electrolysis

Journal article (2020)

Authors

J.W. Haverkort Energy Technology - Mechanical, Maritime and Materials Engineering
H. Rajaei Energy Technology - Mechanical, Maritime and Materials Engineering
Research Group
Energy Technology (Mechanical, Maritime and Materials Engineering) (TU Delft)
Copyright: © 2020 J.W. Haverkort, H. Rajaei
DOI: https://doi.org/10.1016/j.powera.2020.100034
Alkaline water electrolysis Hydrogen purity Limiting current density Microporous separator
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Published Date

2020

Language

English

Faculty

Mechanical, Maritime and Materials Engineering

Department

Process and Energy

Research Group

Energy Technology

Abstract

Under alkaline conditions, hydroxide ions can deplete at the anode of a water electrolyser for hydrogen production, resulting in a limiting current density. We found experimentally that in a micro-porous separator, an electro-osmotic flow from anode to cathode lowers this limiting current density. Using the Nernst-Planck equation, a useful expression for the potential drop in the presence of diffusion, migration, and advection is derived. A quasi-stationary, one-dimensional model is used to successfully describe the transient dynamics. Electro-osmotic flow-driven cross-over of dissolved oxygen is argued to impact the hydrogen purity.