Unlocking the Impact of "Cell Position" on Solid-State Hydrogen Storage: Investigations on an Activated Carbon Electrode Integrated in a Modified Reversible Polymer Electrolyte Membrane Fuel Cell

The presented maiden experimental study introduces a novel cell position concept for a modified reversible polymer electrolyte membrane fuel cell with an integrated hydrogen storage (H-storage) electrode. The primary focus of the current study is to enhance the H-storage capacity of a carbon-based self-standing electrode by testing it in vertical, horizontally upward, and horizontally downward positions to meet U.S. Department of Energy objectives. The results show that the developed cell achieves the highest electrochemical hydrogen adsorption (H-adsorption) of 1.3 weight percent (wt%) in the horizontal downward position during charging, surpassing the vertical position by 36.1% and outperforming the horizontal upward position by 25.3%. The reversible rates of stored hydrogen are measured as 0.587 wt% in the vertical position, 0.781 wt% in the horizontal upward position, and 0.998 wt% in the horizontal downward position. The cell manages to deliver a peak output of 2.2 V and a maximum current of 0.5 mA during the initial discharging phase. The insights gained from this study on cell positioning are poised to inspire future research efforts aimed at enhancing hydrogen storage capacity and its reversibility. The graphical abstract represents two modes of operation of the test cell, viz. electrolyzer-mode (E-mode) and fuel cell-mode (FC-mode). In an E-mode, cell is supplied with water that splits under the influence of the applied power into hydrogen (some of which get adsorbed in carbon electrode) and oxygen. In an FC-mode, the stored hydrogen and oxygen reform water besides giving out electricity.image (c) 2024 WILEY-VCH GmbH