Pub Date : 2024-09-17DOI: 10.1149/1945-7111/ad790a
J. M. Edjokola, M. Heidinger, A. M. Niroumand, V. Hacker and M. Bodner
Gas Diffusion Layers (GDLs) are integral in polymer electrolyte fuel cells, facilitating gas and water transport while providing structural support. However, their susceptibility to chemical degradation significantly impacts their functionality over extensive periods of time. This study investigates the mechanisms of GDL degradation, focusing on chemical oxidation. Accelerated stress testing, which involves immersing GDL in Fenton’s reagent for 24 h, is used. Ex-situ analysis reveals changes in surface properties, including a 3% reduction in contact angle, from 15% to only 9% remaining fluorine on the surface, and OH group presence in GDLs exposed to Fenton’s reagent. In-situ methods are used to study the impact of GDL degradation on fuel cell performance. Polarization curve reveals a 17% performance enhancement in aged GDLs, with a corresponding 19% decrease in voltage loss due to oxygen transport resistance at a high current observed via transient limiting current analysis. Electrochemical impedance spectroscopy reveals a 51% reduction in mass transport resistance, providing insights into structural alterations, such as pore widening and increased hydrophilicity. Despite these improvements, aged GDL demonstrates substantial degradation under high humidity, leading to water management challenges and voltage instability. This is attributed to the loss of fluorine, as indicated by the ex situ analysis.
{"title":"Chemical Oxidation-Induced Degradation in Gas Diffusion Layers for PEFC: Mechanisms and Performance Implications","authors":"J. M. Edjokola, M. Heidinger, A. M. Niroumand, V. Hacker and M. Bodner","doi":"10.1149/1945-7111/ad790a","DOIUrl":"https://doi.org/10.1149/1945-7111/ad790a","url":null,"abstract":"Gas Diffusion Layers (GDLs) are integral in polymer electrolyte fuel cells, facilitating gas and water transport while providing structural support. However, their susceptibility to chemical degradation significantly impacts their functionality over extensive periods of time. This study investigates the mechanisms of GDL degradation, focusing on chemical oxidation. Accelerated stress testing, which involves immersing GDL in Fenton’s reagent for 24 h, is used. Ex-situ analysis reveals changes in surface properties, including a 3% reduction in contact angle, from 15% to only 9% remaining fluorine on the surface, and OH group presence in GDLs exposed to Fenton’s reagent. In-situ methods are used to study the impact of GDL degradation on fuel cell performance. Polarization curve reveals a 17% performance enhancement in aged GDLs, with a corresponding 19% decrease in voltage loss due to oxygen transport resistance at a high current observed via transient limiting current analysis. Electrochemical impedance spectroscopy reveals a 51% reduction in mass transport resistance, providing insights into structural alterations, such as pore widening and increased hydrophilicity. Despite these improvements, aged GDL demonstrates substantial degradation under high humidity, leading to water management challenges and voltage instability. This is attributed to the loss of fluorine, as indicated by the ex situ analysis.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"18 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1149/1945-7111/ad77f5
Wonseok Yang, Suhee Choi, Tae-Hong Park, Sungyeol Choi and Sang-Eun Bae
Understanding the redox reactions of fission products in molten salts is crucial for developing pyroprocessing techniques for used nuclear fuel. A rotating disk electrode is useful for investigating the electrochemical reactions with controlled mass transfer conditions, but its application has been limited in high-temperature corrosive molten salts. This study employs a tungsten (W) rotating disk electrode (RDE) to measure the electrochemical and kinetic properties of the Sm(III)/Sm(II) redox reaction in a LiCl-KCl eutectic molten salt. The properties of the Sm(III)/Sm(II) redox reaction, including diffusion coefficients, exchange current densities, charge transfer coefficients, activation energies, and Tafel slopes, were determined over a temperature range of 723–803 K using limiting currents in linear sweep voltammetry at various rotating speeds and mass transfer-corrected Tafel plots. The kinetic parameters obtained using the rotating disk electrode system can be useful for optimizing the design of pyroprocessing techniques.
了解熔盐中裂变产物的氧化还原反应对于开发废旧核燃料热处理技术至关重要。旋转盘电极可用于研究受控传质条件下的电化学反应，但其在高温腐蚀性熔盐中的应用一直受到限制。本研究采用钨（W）旋转盘电极（RDE）测量锂-氯化钾共晶熔盐中 Sm(III)/Sm(II) 氧化还原反应的电化学和动力学特性。在 723-803 K 的温度范围内，利用线性扫描伏安法在不同转速下的极限电流和传质校正塔菲尔图，测定了 Sm(III)/Sm(II) 氧化还原反应的特性，包括扩散系数、交换电流密度、电荷转移系数、活化能和塔菲尔斜率。使用旋转盘电极系统获得的动力学参数有助于优化热处理技术的设计。
{"title":"Rotating Disk Electrode Study of Sm(III)/Sm(II) in LiCl-KCl Eutectic Molten Salt","authors":"Wonseok Yang, Suhee Choi, Tae-Hong Park, Sungyeol Choi and Sang-Eun Bae","doi":"10.1149/1945-7111/ad77f5","DOIUrl":"https://doi.org/10.1149/1945-7111/ad77f5","url":null,"abstract":"Understanding the redox reactions of fission products in molten salts is crucial for developing pyroprocessing techniques for used nuclear fuel. A rotating disk electrode is useful for investigating the electrochemical reactions with controlled mass transfer conditions, but its application has been limited in high-temperature corrosive molten salts. This study employs a tungsten (W) rotating disk electrode (RDE) to measure the electrochemical and kinetic properties of the Sm(III)/Sm(II) redox reaction in a LiCl-KCl eutectic molten salt. The properties of the Sm(III)/Sm(II) redox reaction, including diffusion coefficients, exchange current densities, charge transfer coefficients, activation energies, and Tafel slopes, were determined over a temperature range of 723–803 K using limiting currents in linear sweep voltammetry at various rotating speeds and mass transfer-corrected Tafel plots. The kinetic parameters obtained using the rotating disk electrode system can be useful for optimizing the design of pyroprocessing techniques.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"11 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1149/1945-7111/ad7535
A. Korjenic, E. Romanovskaia and J. R. Scully
The scanning vibrating electrode technique (SVET) was utilized to monitor localized corrosion and substrate protection of three metal-rich primers (MRP). The ability to suppress localized corrosion and provide widespread cathodic polarization to enable sacrificial anode-based cathodic protection of a AA 7075-T651 substrate with either an aluminum-rich primer (AlRP), magnesium-rich primer (MgRP), or a composite magnesium + aluminum-rich primer (MgAlRP) in a polyamide-based epoxy primer coatings fully immersed in 1 mM NaCl was investigated. Pigments did not activate uniformly in each MRP. The notion of throwing power polarizing the bare substrate and uniform current and potential distributions at scratch sites does not describe the behavior observed. In cases where activation occurred, protection was noticed in the form of suppression of local anodes on bare AA 7075-T651. Local corrosion was suppressed on heterogeneously corroding AA 7075-T651 with strong local anodes and cathodes. Widespread cathodic polarization was absent. The MgRP and MgAlRP were shown to provide superior local corrosion suppression associated with pitting on AA 7075-T651 compared to the AlRP.
利用扫描振动电极技术（SVET）监测了三种富金属底漆（MRP）的局部腐蚀和基底保护情况。研究了在完全浸入 1 mM NaCl 的聚酰胺基环氧底漆涂层中使用富铝底漆 (AlRP)、富镁底漆 (MgRP) 或复合富镁 + 铝底漆 (MgAlRP) 对 AA 7075-T651 基材进行抑制局部腐蚀和提供广泛阴极极化以实现牺牲阳极阴极保护的能力。颜料在每种 MRP 中的活化程度并不一致。投掷功率极化裸基材以及划痕处电流和电位分布均匀的概念并不能描述所观察到的行为。在发生活化的情况下，裸 AA 7075-T651 上的局部阳极受到抑制，从而起到保护作用。在具有强局部阳极和阴极的异质腐蚀 AA 7075-T651 上，局部腐蚀被抑制。不存在广泛的阴极极化现象。与 AlRP 相比，MgRP 和 MgAlRP 能更好地抑制 AA 7075-T651 上与点蚀相关的局部腐蚀。
{"title":"Spatially Resolved Assessment and Analysis of Al-Zn, Mg, and Mg/Al-Zn Metal-Rich Primers Applied to AA 7075-T651 in Full Immersion","authors":"A. Korjenic, E. Romanovskaia and J. R. Scully","doi":"10.1149/1945-7111/ad7535","DOIUrl":"https://doi.org/10.1149/1945-7111/ad7535","url":null,"abstract":"The scanning vibrating electrode technique (SVET) was utilized to monitor localized corrosion and substrate protection of three metal-rich primers (MRP). The ability to suppress localized corrosion and provide widespread cathodic polarization to enable sacrificial anode-based cathodic protection of a AA 7075-T651 substrate with either an aluminum-rich primer (AlRP), magnesium-rich primer (MgRP), or a composite magnesium + aluminum-rich primer (MgAlRP) in a polyamide-based epoxy primer coatings fully immersed in 1 mM NaCl was investigated. Pigments did not activate uniformly in each MRP. The notion of throwing power polarizing the bare substrate and uniform current and potential distributions at scratch sites does not describe the behavior observed. In cases where activation occurred, protection was noticed in the form of suppression of local anodes on bare AA 7075-T651. Local corrosion was suppressed on heterogeneously corroding AA 7075-T651 with strong local anodes and cathodes. Widespread cathodic polarization was absent. The MgRP and MgAlRP were shown to provide superior local corrosion suppression associated with pitting on AA 7075-T651 compared to the AlRP.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"48 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1149/1945-7111/ad7890
Ankita Pal, Nanda Gopala Krishna, Ravi Shankar A. and John Philip
In the current study, we report for the first time the observation of unintended localized surface modification on commercially pure aluminum (Al) during an alternating current scanning electrochemical microscopy (AC-SECM) analysis, its origin, and the probable mechanism responsible for it. Application of an AC perturbation potential (∼100 mV amplitude at ∼100 kHz frequency) to the Platinum ultramicroelectrode (Pt UME), during AC-SECM in acidic, neutral chloride, tap water, and alkaline electrolytes was found to cause surface modification on the scanned region of Al. An increase in the local pH of the electrolyte between the UME and the Al substrate, irrespective of the electrolyte pH (3–11) and UME biasing conditions, led to the local surface modification. The reason for the enhancement of local pH is attributed to the occurrence of higher rates of cathodic reduction reactions than that of anodic oxidation reactions. The reduction of dissolved oxygen/protons/water in the electrolytes led to the generation or consumption of OH−/H+ ions, respectively, and thus increased the pH, whereas the oxidation of Pt UME/Al surfaces decreased the pH with the generation of H+ or consumption of OH− ions. These results contribute significantly to accurately analyzing Al and its alloys using the AC-SECM technique.
{"title":"Localized Surface Modification during Alternating Current Scanning Electrochemical Microscopy: Origin and Mechanism","authors":"Ankita Pal, Nanda Gopala Krishna, Ravi Shankar A. and John Philip","doi":"10.1149/1945-7111/ad7890","DOIUrl":"https://doi.org/10.1149/1945-7111/ad7890","url":null,"abstract":"In the current study, we report for the first time the observation of unintended localized surface modification on commercially pure aluminum (Al) during an alternating current scanning electrochemical microscopy (AC-SECM) analysis, its origin, and the probable mechanism responsible for it. Application of an AC perturbation potential (∼100 mV amplitude at ∼100 kHz frequency) to the Platinum ultramicroelectrode (Pt UME), during AC-SECM in acidic, neutral chloride, tap water, and alkaline electrolytes was found to cause surface modification on the scanned region of Al. An increase in the local pH of the electrolyte between the UME and the Al substrate, irrespective of the electrolyte pH (3–11) and UME biasing conditions, led to the local surface modification. The reason for the enhancement of local pH is attributed to the occurrence of higher rates of cathodic reduction reactions than that of anodic oxidation reactions. The reduction of dissolved oxygen/protons/water in the electrolytes led to the generation or consumption of OH−/H+ ions, respectively, and thus increased the pH, whereas the oxidation of Pt UME/Al surfaces decreased the pH with the generation of H+ or consumption of OH− ions. These results contribute significantly to accurately analyzing Al and its alloys using the AC-SECM technique.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"34 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1149/1945-7111/ad7987
Irina-Alina Chera-Anghel, Raluca-Ioana Stefan-van Staden, Catalina Cioates Negut and Jacobus Frederick van Staden
Ochratoxine A is a very stable mycotoxin which cannot be destroyed below 250°C. Found in grains, coffee, grapes, wine, milk, and meat, it can produce kidney damage and cancer. Therefore, a smartphone operated intellingent stochastic miniplatform was designed, characterised, and validated for the on-site screening of milk for fast determination of ochratoxine A. (Z)-N-[2-(4-hydroxyphenyl) ethyl]octadec-9-enamide was used as modifier of a gold matrix for a screen printed stochastic sensor used as sensing tool in the design of the miniplatform. A wide linear concentration range (1.0 × 10−15 − 1.0 × 10−7 mol l‒1) and a low limit of quantification of 1 fmol l‒1 were achieved for the assay of ochratoxin A. Recovery values higher than 99.00% were obtained for ochratoxine A, when the miniplatform was used for the screening of cow’s milk and vegetarian milk.
赭曲霉毒素 A 是一种非常稳定的霉菌毒素，在 250°C 以下无法被破坏。它存在于谷物、咖啡、葡萄、葡萄酒、牛奶和肉类中，可导致肾损伤和癌症。(Z)-N-[2-(4-羟基苯基)乙基]十八-9-烯酰胺被用作丝网印刷随机传感器的金基质改性剂，丝网印刷随机传感器被用作微型平台设计中的传感工具。赭曲霉毒素 A 的检测达到了较宽的线性浓度范围（1.0 × 10-15 - 1.0 × 10-7 mol l-1）和较低的定量限（1 fmol l-1）。
{"title":"A Smartphone Operated Intelligent Stochastic Miniplatform for On-Site Screening of Milk for Fast Determination of Ochratoxin A","authors":"Irina-Alina Chera-Anghel, Raluca-Ioana Stefan-van Staden, Catalina Cioates Negut and Jacobus Frederick van Staden","doi":"10.1149/1945-7111/ad7987","DOIUrl":"https://doi.org/10.1149/1945-7111/ad7987","url":null,"abstract":"Ochratoxine A is a very stable mycotoxin which cannot be destroyed below 250°C. Found in grains, coffee, grapes, wine, milk, and meat, it can produce kidney damage and cancer. Therefore, a smartphone operated intellingent stochastic miniplatform was designed, characterised, and validated for the on-site screening of milk for fast determination of ochratoxine A. (Z)-N-[2-(4-hydroxyphenyl) ethyl]octadec-9-enamide was used as modifier of a gold matrix for a screen printed stochastic sensor used as sensing tool in the design of the miniplatform. A wide linear concentration range (1.0 × 10−15 − 1.0 × 10−7 mol l‒1) and a low limit of quantification of 1 fmol l‒1 were achieved for the assay of ochratoxin A. Recovery values higher than 99.00% were obtained for ochratoxine A, when the miniplatform was used for the screening of cow’s milk and vegetarian milk.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"19 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1149/1945-7111/ad7891
Yan Su, Ben Yang, Xinwei Xu, Maosheng Jing, Xinnian Meng and Yongming Tang
An approach to encapsulate zinc powder by in situ polymerization of aniline (PANI@Zn) is developed for Zn-rich epoxy coatings (ZRCs). With the application of PANI@Zn composites in the ZRCs, the encapsulated zinc particles are not activated due to the corrosion inhibition of PANI at the early stage of immersion, and physical shielding being mainly responsible for the protection of the steel substrate. At the stage of cathodic protection, the consumption of zinc powder is relatively uniform from the outer layer to the inner layer of the coating PANI@Zn coating, and the utilization rate of zinc powder is higher than that in the coating incorporated by the raw zinc powder. The required amount of zinc powder for achieving the same protective effect as the case of the raw zinc powder is reduced by ca. 20% after the application of the PANI@Zn composites.
{"title":"In Situ PANI Encapsulation of Zinc Powder Enhancing the Corrosion Resistance of Zinc-Rich Epoxy Coatings","authors":"Yan Su, Ben Yang, Xinwei Xu, Maosheng Jing, Xinnian Meng and Yongming Tang","doi":"10.1149/1945-7111/ad7891","DOIUrl":"https://doi.org/10.1149/1945-7111/ad7891","url":null,"abstract":"An approach to encapsulate zinc powder by in situ polymerization of aniline (PANI@Zn) is developed for Zn-rich epoxy coatings (ZRCs). With the application of PANI@Zn composites in the ZRCs, the encapsulated zinc particles are not activated due to the corrosion inhibition of PANI at the early stage of immersion, and physical shielding being mainly responsible for the protection of the steel substrate. At the stage of cathodic protection, the consumption of zinc powder is relatively uniform from the outer layer to the inner layer of the coating PANI@Zn coating, and the utilization rate of zinc powder is higher than that in the coating incorporated by the raw zinc powder. The required amount of zinc powder for achieving the same protective effect as the case of the raw zinc powder is reduced by ca. 20% after the application of the PANI@Zn composites.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"46 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-16DOI: 10.1149/1945-7111/ad76da
Alexander Karger, Simon E. J. O’Kane, Marcel Rogge, Cedric Kirst, Jan P. Singer, Monica Marinescu, Gregory J. Offer and Andreas Jossen
Degradation models are important tools for understanding and mitigating lithium-ion battery aging, yet a universal model that can predict degradation under all operating conditions remains elusive. One challenge is the coupled influence of calendar and cycle aging phases on degradation mechanisms, such as solid electrolyte interphase (SEI) formation. In this work, we identify and systematically compare three different SEI interaction theories found in the literature, and apply them to experimental degradation data from a commercial lithium-ion cell. In a step-by-step process, and after careful data selection, we show that SEI delamination without any cracking of the active particles, and SEI microcracking, where cycling only affects SEI growth during the cycle itself, are both unlikely candidates. Instead, the results indicate that upon cycling, both the SEI and the active particle crack, and we provide a simple, 4-parameter equation that can predict the particle crack rate. Contrary to the widely-accepted Paris’ law, the particle crack rate decreases with increasing cycles, potentially due to changing intercalation dynamics resulting from the increasing surface-to-volume ratio of the active particles. The proposed model predicts SEI formation accurately at different storage conditions, while simply adding the degradation from pure calendar and cycle aging underestimates the total degradation.
降解模型是了解和缓解锂离子电池老化的重要工具，然而，能够预测所有工作条件下降解情况的通用模型仍然遥不可及。其中一个挑战是日历和循环老化阶段对降解机制的耦合影响，例如固体电解质相（SEI）的形成。在这项工作中，我们确定并系统比较了文献中三种不同的 SEI 相互作用理论，并将它们应用到商用锂离子电池的实验降解数据中。经过一步步的研究和对数据的仔细筛选，我们发现，没有任何活性颗粒裂纹的 SEI 分层和 SEI 微裂纹（循环仅在循环过程中影响 SEI 的生长）都是不可能的候选理论。相反，结果表明，在循环过程中，SEI 和活性颗粒都会开裂，我们提供了一个简单的 4 参数方程，可以预测颗粒开裂率。与广为接受的帕里斯定律相反，颗粒开裂率会随着循环次数的增加而降低，这可能是由于活性颗粒的表面体积比不断增加，导致插层动力学发生了变化。所提出的模型可以准确预测不同存储条件下 SEI 的形成，而简单地将纯日历和循环老化产生的降解相加，则会低估总降解量。
{"title":"Modeling Particle Versus SEI Cracking in Lithium-Ion Battery Degradation: Why Calendar and Cycle Aging Cannot Simply be Added","authors":"Alexander Karger, Simon E. J. O’Kane, Marcel Rogge, Cedric Kirst, Jan P. Singer, Monica Marinescu, Gregory J. Offer and Andreas Jossen","doi":"10.1149/1945-7111/ad76da","DOIUrl":"https://doi.org/10.1149/1945-7111/ad76da","url":null,"abstract":"Degradation models are important tools for understanding and mitigating lithium-ion battery aging, yet a universal model that can predict degradation under all operating conditions remains elusive. One challenge is the coupled influence of calendar and cycle aging phases on degradation mechanisms, such as solid electrolyte interphase (SEI) formation. In this work, we identify and systematically compare three different SEI interaction theories found in the literature, and apply them to experimental degradation data from a commercial lithium-ion cell. In a step-by-step process, and after careful data selection, we show that SEI delamination without any cracking of the active particles, and SEI microcracking, where cycling only affects SEI growth during the cycle itself, are both unlikely candidates. Instead, the results indicate that upon cycling, both the SEI and the active particle crack, and we provide a simple, 4-parameter equation that can predict the particle crack rate. Contrary to the widely-accepted Paris’ law, the particle crack rate decreases with increasing cycles, potentially due to changing intercalation dynamics resulting from the increasing surface-to-volume ratio of the active particles. The proposed model predicts SEI formation accurately at different storage conditions, while simply adding the degradation from pure calendar and cycle aging underestimates the total degradation.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"94 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-15DOI: 10.1149/1945-7111/ad749f
Tim Dörenkamp, Mayank Sabharwal, Federica Marone, Felix N. Büchi, Thomas J. Schmidt and Jens Eller
Efficient removal of the electrochemically produced water from the gas diffusion layer (GDL) in polymer electrolyte fuel cells is crucial for reducing mass transport losses and improving the efficiency at high current densities. Understanding the relationship between the water percolation through the GDL and droplet formation in the gas channel will allow the design of advanced GDL materials, which provide optimal water management. In this study, a catalyst-coated membrane with 8 individual active areas (0.06 mm2 each) is investigated using operando X-ray tomographic microscopy to study the transient development and interaction of multiple percolating water clusters in a GDL and droplet formation in the channel. The 4D imaging results at a time resolution of 1 Hz showed transient instabilities in the developed percolating water networks at various frequencies associated with break-through and spontaneous water drainage.
{"title":"Investigation of Dynamic Water Cluster and Droplet Interactions in Polymer Electrolyte Fuel Cells using Operando X-ray Tomographic Microscopy","authors":"Tim Dörenkamp, Mayank Sabharwal, Federica Marone, Felix N. Büchi, Thomas J. Schmidt and Jens Eller","doi":"10.1149/1945-7111/ad749f","DOIUrl":"https://doi.org/10.1149/1945-7111/ad749f","url":null,"abstract":"Efficient removal of the electrochemically produced water from the gas diffusion layer (GDL) in polymer electrolyte fuel cells is crucial for reducing mass transport losses and improving the efficiency at high current densities. Understanding the relationship between the water percolation through the GDL and droplet formation in the gas channel will allow the design of advanced GDL materials, which provide optimal water management. In this study, a catalyst-coated membrane with 8 individual active areas (0.06 mm2 each) is investigated using operando X-ray tomographic microscopy to study the transient development and interaction of multiple percolating water clusters in a GDL and droplet formation in the channel. The 4D imaging results at a time resolution of 1 Hz showed transient instabilities in the developed percolating water networks at various frequencies associated with break-through and spontaneous water drainage.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"64 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-15DOI: 10.1149/1945-7111/ad778f
Ling Ran, Jie Li, Zhong Zou, Bo Zhang, Quanlin Li, Shuai Yang and Hongliang Zhang
Aluminum electrolysis cells (AECs) require effective thermal regulation to operate flexibly alongside renewable energy sources. Prior to implementing thermal regulation strategies, it is essential to predict the dynamic variations in the thermal field and ledge characteristics of a full-scale cell. This study introduces a transient electro-thermal-flow coupling model for a full-scale AEC, aimed at investigating the interactions between ledge distribution and various operational fields, including thermal, electric, and flow fields. The model facilitates the calculation and assessment of the dynamic properties of the ledge and thermal balance under ±15% flexible current variations. Results indicate that during a current increase, ledge melting predominantly occurs in the electrolyte layer, while ledge solidification is primarily observed in the metal layer during a current reduction. Regions with a thicker ledge and faster velocity tend to melt more during current increases and are less likely to return to their original shape and thickness during current reductions, complicating the rapid restoration of thermal equilibrium. To achieve uniform ledge distribution and real-time adaptation to flexible current variations, it is recommended to install distributed cooling devices on the sides of the AEC to enable differential ledge regulation at various locations.
{"title":"Fully-Coupled Electric-Thermal-Flow Modeling and Investigation of Dynamic Thermal-Ledge Behavior in Aluminum Electrolysis Cell","authors":"Ling Ran, Jie Li, Zhong Zou, Bo Zhang, Quanlin Li, Shuai Yang and Hongliang Zhang","doi":"10.1149/1945-7111/ad778f","DOIUrl":"https://doi.org/10.1149/1945-7111/ad778f","url":null,"abstract":"Aluminum electrolysis cells (AECs) require effective thermal regulation to operate flexibly alongside renewable energy sources. Prior to implementing thermal regulation strategies, it is essential to predict the dynamic variations in the thermal field and ledge characteristics of a full-scale cell. This study introduces a transient electro-thermal-flow coupling model for a full-scale AEC, aimed at investigating the interactions between ledge distribution and various operational fields, including thermal, electric, and flow fields. The model facilitates the calculation and assessment of the dynamic properties of the ledge and thermal balance under ±15% flexible current variations. Results indicate that during a current increase, ledge melting predominantly occurs in the electrolyte layer, while ledge solidification is primarily observed in the metal layer during a current reduction. Regions with a thicker ledge and faster velocity tend to melt more during current increases and are less likely to return to their original shape and thickness during current reductions, complicating the rapid restoration of thermal equilibrium. To achieve uniform ledge distribution and real-time adaptation to flexible current variations, it is recommended to install distributed cooling devices on the sides of the AEC to enable differential ledge regulation at various locations.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"30 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-15DOI: 10.1149/1945-7111/ad76de
Rankin Shum, Marah Cragun, Tyler Williams and Devin Rappleye
Residual water in molten CaCl2 reacts to form different byproducts, such as HCl, which can impact the corrosivity of the salt and efficiency of electrochemical operations, such as electrolytic oxide reduction and electrorefining. The ability to detect and quantify these byproducts electrochemically can provide feedback on the efficacy of vacuum drying and other purification methods, as well as the impact of these byproducts on process operations. An electrochemical signal’s association with the production of H2 is verified and characterized using cyclic voltammetry (CV) and residual gas analysis. CV estimated a 2-electron exchange process associated with H2 production. CV detected trace quantities of an oxidized species containing hydrogen in the salt on the order of 10 ppm. Different salt handling methods were compared for their impact on the hydrogen electrochemical signal. It was found that 30 min of exposure of CaCl2 in a beaker to low-humidity air (<20%) had minimal impact on the H2 production signal.
{"title":"Electrochemical Investigation of Moisture Byproducts in Molten Calcium Chloride","authors":"Rankin Shum, Marah Cragun, Tyler Williams and Devin Rappleye","doi":"10.1149/1945-7111/ad76de","DOIUrl":"https://doi.org/10.1149/1945-7111/ad76de","url":null,"abstract":"Residual water in molten CaCl2 reacts to form different byproducts, such as HCl, which can impact the corrosivity of the salt and efficiency of electrochemical operations, such as electrolytic oxide reduction and electrorefining. The ability to detect and quantify these byproducts electrochemically can provide feedback on the efficacy of vacuum drying and other purification methods, as well as the impact of these byproducts on process operations. An electrochemical signal’s association with the production of H2 is verified and characterized using cyclic voltammetry (CV) and residual gas analysis. CV estimated a 2-electron exchange process associated with H2 production. CV detected trace quantities of an oxidized species containing hydrogen in the salt on the order of 10 ppm. Different salt handling methods were compared for their impact on the hydrogen electrochemical signal. It was found that 30 min of exposure of CaCl2 in a beaker to low-humidity air (<20%) had minimal impact on the H2 production signal.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"3 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：