Electrodes: Flat vs Pin-Type Topology in Alkaline Water Electrolysis

Abstract

The energy transition is already underway, and hydrogen plays a crucial role by enabling renewable energy storage without emitting carbon dioxide and other greenhouse gases. Given the intermittency of renewable energy sources, energy storage is essential in this transition. Hydrogen technologies are recognized as promising solutions. One method to produce green hydrogen is through water electrolysis using renewable energy sources, a process identified with significant potential for decarbonization. However, it needs to enhance efficiency, reduce component costs, and consequently, production costs to expand its adoption. Alkaline water electrolysis for hydrogen production is a mature technology with commercially available megawatt (MW) scale installations. To enhance the performance of alkaline electrolyzers, this study focuses on evaluating flat and pin-type electrodes. To analyze their performance, the electrodes were tested at, 20 degrees Celsius, varying electrode distances between them. Tests were conducted in an electrochemical cell, where different operating voltages were applied incrementally, from 0.1 [V] every 30 seconds, across a range of 0 to 2.7 [V]. From the analyzed distances, the highest current densities were obtained at 1.95 [mm] for the pin type and 4.59 [mm] for the flat. Comparing performances at comparable distances, it is observed that the flat electrode generates a higher current density than the pin type. Although the pin-type electrode increases its surface area by approximately 83%, it hinders the detachment of bubbles, causing them to remain on the electrode’s surface for a longer time and reducing its performance.