Observation of Preferential Pathways for Oxygen Removal through Porous Transport Layers of Polymer Electrolyte Water Electrolyzers

Pongsarun Satjaritanun; Maeve O'Brien; Devashish Kulkarni; Sirivatch Shimpalee; Cristopher Capuano; Katherine E Ayers; Nemanja Danilovic; Dilworth Y Parkinson; Iryna V Zenyuk

doi:10.1016/j.isci.2020.101783

Observation of Preferential Pathways for Oxygen Removal through Porous Transport Layers of Polymer Electrolyte Water Electrolyzers

iScience. 2020 Nov 9;23(12):101783. doi: 10.1016/j.isci.2020.101783. eCollection 2020 Dec 18.

Authors

Pongsarun Satjaritanun¹, Maeve O'Brien², Devashish Kulkarni², Sirivatch Shimpalee³, Cristopher Capuano⁴, Katherine E Ayers⁴, Nemanja Danilovic⁵, Dilworth Y Parkinson⁵, Iryna V Zenyuk^{1

2}

Affiliations

¹ Department of Chemical and Biomolecular Engineering, National Fuel Cell Research Center, University of California Irvine, Irvine, CA, USA.
² Department of Material Science and Engineering, University of California Irvine, Irvine, CA, USA.
³ Department of Chemical Engineering, University of South Carolina, Columbia, SC, USA.
⁴ Nel Hydrogen, Wallingford, CT, USA.
⁵ Lawrence Berkeley National Laboratory, Berkeley, CA, USA.

Abstract

Understanding the relationships between porous transport layer (PTL) morphology and oxygen removal is essential to improve the polymer electrolyte water electrolyzer (PEWE) performance. Operando X-ray computed tomography and machine learning were performed on a model electrolyzer at different water flow rates and current densities to determine how these operating conditions alter oxygen transport in the PTLs. We report a direct observation of oxygen taking preferential pathways through the PTL, regardless of the water flow rate or current density (1-4 A/cm²). Oxygen distribution in the PTL had a periodic behavior with period of 400 μm. A computational fluid dynamics model was used to predict oxygen distribution in the PTL showing periodic oxygen front. Observed oxygen distribution is due to low in-plane PTL tortuosity and high porosity enabling merging of oxygen bubbles in the middle of the PTL and also due to aerophobicity of the layer.

Keywords: Chemical Engineering; Chemistry; Electrochemical Energy Conversion; Electrochemistry; Energy Materials.