Impact of an electrode-diaphragm gap on diffusive hydrogen crossover in alkaline water electrolysis.

This is the metadata for the research paper "Impact of an electrode-diaphragm gap on diffusive hydrogen crossover in alkaline water electrolysis".

In this study we further explore how the hydrogen crossover flux depends on the electrode-diaphragm configuration with a special focus on the influence of the gap distance between the electrode and the diaphragm. Therefore, a comparison of finite- and zero-gap AWE designs is made using Zirfon PERL UTP 220 and Zirfon Perl UTP 500. The effect of a finite gap is investigated both at the anodic and cathodic side. Special attention is given to reproducibility, which appears to be a major challenge between different experiments. We carry out gas crossover experiments using gas chromatography at current densities ranging from 0.1 to 0.3 A.cm-², which are representative values for the minimum load of alkaline electrolyzers.

ABSTRACT
Hydrogen crossover limits the load range of alkaline water electrolyzers, hindering their integration with renewable energy. This study examines the impact of the electrode-diaphragm gap on crossover, focusing on diffusive transport. Both finite-gap and zero-gap designs employing the state-of-the-art Zirfon UTP Perl 500 and UTP 220 diaphragms were investigated at room temperature and with a 12 wt.% KOH electrolyte. Experimental results reveal a relatively high crossover for a zero-gap configuration, which corresponds to supersaturation levels at the diaphragm-electrolyte interface of 8-80, with significant fluctuations over time and between experiments due to an imperfect zero-gap design. In contrast, a finite-gap (500 μm) has a significantly smaller crossover, corresponding to supersaturation levels of 2-4. Introducing a cathode gap strongly decreases crossover, unlike an anode gap. Our results suggest that adding a small cathode-gap can significantly decrease gas impurity, potentially increase the operating range of alkaline electrolyzers, while maintaining good efficiency.

本元数据对应研究论文《电极-隔膜间隙对碱性水电解槽中扩散性氢穿渗的影响》（Impact of an electrode-diaphragm gap on diffusive hydrogen crossover in alkaline water electrolysis）。

本研究进一步探究氢穿渗（hydrogen crossover）通量如何随电极-隔膜构型变化，重点关注电极与隔膜之间的间隙距离的影响。为此，本研究采用Zirfon PERL UTP 220与Zirfon Perl UTP 500两种隔膜，对比有限间隙与零间隙碱性水电解（alkaline water electrolysis, AWE）装置的设计性能。研究同时考察了阳极侧（anodic side）与阴极侧（cathodic side）的有限间隙效应。本研究特别关注实验可重复性问题——该问题在不同实验间始终是一项重大挑战。实验中，我们采用气相色谱法（gas chromatography）开展气体穿渗测试，测试电流密度（current density）范围为0.1至0.3 A·cm⁻²，该范围覆盖碱性水电解槽的最低运行负载典型值。

摘要
氢穿渗（hydrogen crossover）限制了碱性水电解槽的负载运行范围，阻碍了其与可再生能源的集成适配。本研究聚焦扩散输运过程，考察了电极-隔膜间隙对氢穿渗的影响。研究针对室温下采用12%质量分数氢氧化钾（KOH）电解液的工况，对采用当前主流Zirfon UTP Perl 500与UTP 220隔膜的有限间隙与零间隙两种设计方案开展了测试。实验结果显示，零间隙构型下的氢穿渗程度相对较高，对应隔膜-电解液界面的过饱和度（supersaturation）为8~80；同时由于零间隙设计存在瑕疵，实验过程中以及不同实验间的穿渗水平存在显著波动。与之形成对比的是，500 μm的有限间隙构型下的氢穿渗程度显著更低，对应过饱和度仅为2~4。相较于阳极间隙，增设阴极间隙可大幅降低氢穿渗水平。本研究结果表明，增设小型阴极间隙可显著降低气体杂质含量，在维持良好运行效率的同时，有望拓展碱性水电解槽的运行负载范围。