Reaction characteristics of molten carbonate cell operated in fuel cell and electrolysis modes with reactant gas addition method

IF 4.5 3区化学 Q1 Chemical Engineering Journal of Electroanalytical Chemistry Pub Date : 2023-08-15 DOI:10.1016/j.jelechem.2023.117577

Samuel Koomson, Choong-Gon Lee

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Abstract

This work compares the electrode reaction mechanisms of 100 cm² class molten carbonate cells (MCCs) operated in electrolysis cell (EC) and fuel cell (FC) modes using a reactant gas addition (RA) method. The RA method reveals essential information on an electrode reaction mechanism by measuring the overpotential of an electrode resulting from adding a reactant. The hydrogen electrode (HE) is revealed to be under a gas-phase mass transfer-controlled process in both modes. In addition, the HE overpotential at an inlet composition of H₂: CO₂: H₂O = 0.3: 0.3: 0.4 atm is caused mainly by H₂ species in FC mode, while CO₂ contributes the majority in EC mode due to the production of H₂ and consumption of CO₂ by the water–gas shift reaction. On the other hand, most of the oxygen electrode (OE) overpotential is contributed by O₂ species in both modes. The overpotential induced by O₂ species was larger in FC mode than EC mode because EC mode generates O₂ and provides less mass transfer resistance of O₂ species in the liquid phase. The addition of CO₂ to the OE raised overpotential in both modes. The overpotential was especially large in FC mode due to the reduced O₂ partial pressure and relatively low in EC mode because of O₂ generation. Therefore, the total overpotential in EC mode is less than in FC mode.

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熔融碳酸盐电池在燃料电池和反应物气体加入法电解模式下的反应特性

本研究使用反应物气体添加(RA)方法，比较了在电解电池(EC)和燃料电池(FC)模式下运行的100 cm2级熔融碳酸盐电池(MCCs)的电极反应机制。RA方法通过测量由于加入反应物而产生的电极过电位来揭示电极反应机理的基本信息。在两种模式下，氢电极(HE)都处于气相传质控制过程。此外，在入口组成H2: CO2: H2O = 0.3: 0.3: 0.4 atm时，FC模式下的HE过电位主要由H2种引起，而EC模式下的HE过电位主要是由水煤气变换反应产生H2和消耗CO2引起的。另一方面，在两种模式下，大部分氧电极(OE)过电位都是由O2种贡献的。FC模式下O2种诱导的过电位大于EC模式，这是因为EC模式产生O2，并且在液相中O2种的传质阻力较小。在这两种模式下，向OE中加入二氧化碳会提高过电位。在FC模式下，由于O2分压降低，过电位特别大，而在EC模式下，由于O2的产生，过电位相对较低。因此，EC模式的总过电位小于FC模式。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Electroanalytical Chemistry Chemical Engineering-General Chemical Engineering

CiteScore

7.50

自引率

6.70%

发文量

912

审稿时长

>12 weeks

期刊介绍： The Journal of Electroanalytical Chemistry is the foremost international journal devoted to the interdisciplinary subject of electrochemistry in all its aspects, theoretical as well as applied. Electrochemistry is a wide ranging area that is in a state of continuous evolution. Rather than compiling a long list of topics covered by the Journal, the editors would like to draw particular attention to the key issues of novelty, topicality and quality. Papers should present new and interesting electrochemical science in a way that is accessible to the reader. The presentation and discussion should be at a level that is consistent with the international status of the Journal. Reports describing the application of well-established techniques to problems that are essentially technical will not be accepted. Similarly, papers that report observations but fail to provide adequate interpretation will be rejected by the Editors. Papers dealing with technical electrochemistry should be submitted to other specialist journals unless the authors can show that their work provides substantially new insights into electrochemical processes.