Current Density – Voltage (i-V) Dependence of Polymer Electrolyte Electrochemical Cells (PEEC) on The Cell Components of Gas Diffusion Layers (GDLs) and Cell Sealings

Hydrogen production using water electrolysis in polymer electrolyte electrochemical cells (PEEC) is an attractive technique. The PEEC is known to be relatively strong for input energy fluctuation from a reliability point of view; thus, it is a suitable technique for fluctuating renewable energy storage.<br/>The current density characteristics as a function of PEEC voltage are critical for improving the efficiency of hydrogen production from renewable energies. Research is continuing to improve an oxygen evolution catalyst whose overvoltage is relatively high compared to that of hydrogen evolution and using a thinner polymer electrolyte membrane to reduce the series resistance.<br/>The PEEC cell structure consists of endplates, gas diffusion layers (GDLs), catalyst-coated membranes (CCM), and gas and supplied water-sealing materials. These components were not considered to improve PEEC performance. However, these structures affect electron, water, and gas electron flows. Thus, the effect of these components on the PEEC performance is discussed here.<br/>The influence of the GDL thickness and porosity was evaluated by current density-voltage (i-V) characteristics and electrochemical impedance spectroscopy (EIS). A PEEC with a thicker and higher porosity GDL improved the i-V characteristics. It was also found that the thickness of the seal has an appropriate relationship with the internal parts. The series resistance evaluated by EIS decreased with an improvement in the i-V performance. From these results, the reason for this i-V characteristic change is estimated to be changing the flow of electrons and/or the flows of the source material of water and/or of the produced gas oxygen or hydrogen.