Pub Date : 2024-09-18DOI: 10.1149/1945-7111/ad7765
Filip Adam Dorau, Alessandro Sommer, Jan Koloch, Richard Röß-Ohlenroth, Markus Schreiber, Maximilian Neuner, Kareem Abo Gamra, Yilei Lin, Jan Schöberl, Philip Bilfinger, Sophie Grabmann, Benedikt Stumper, Leon Katzenmeier, Markus Lienkamp and Rüdiger Daub
Considering the growing need for extensive energy storage solutions in smart grid technologies and affordable options for entry-level electric vehicles, sodium-ion batteries offer a promising alternative. They use raw materials that are cheaper, less toxic, and more abundant than those used in lithium-ion batteries, making them especially suitable for large-scale applications. This study comprehensively investigated four commercially available sodium-ion batteries to examine their structural and electrochemical characteristics. The cells were dissected, and the electrode dimensions, the areal mass loadings, and the material compositions were analyzed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, powder X-ray diffraction, and attenuated total reflection Fourier-transform infrared spectroscopy. Electrical characterization, including electrochemical impedance spectroscopy, C-rate testing up to 6 C under different ambient temperatures, along with cyclic aging studies, provided insights into the cells’ performance and degradation mechanisms. The findings highlighted variations in electrode coatings, particle sizes, and cathode materials among the cells, which were then correlated with their electrical behavior. This emphasized the challenges in maintaining sodium-ion battery performance, especially at low temperatures. This study was designed to establish a comprehensive knowledge base for both academic and industrial research in sodium-ion battery technology.
考虑到智能电网技术对广泛储能解决方案的需求日益增长，以及入门级电动汽车的经济实惠，钠离子电池提供了一种前景广阔的替代方案。与锂离子电池相比，钠离子电池使用的原材料更便宜、毒性更低、资源更丰富，因此特别适合大规模应用。本研究全面调查了四种市售钠离子电池，以研究其结构和电化学特性。研究人员解剖了电池，并使用扫描电子显微镜、能量色散 X 射线光谱仪、粉末 X 射线衍射仪和衰减全反射傅立叶变换红外光谱仪分析了电极尺寸、平均质量负载和材料成分。电学表征包括电化学阻抗光谱、不同环境温度下高达 6 C 的 C 速率测试以及循环老化研究，这些研究有助于深入了解电池的性能和降解机制。研究结果突显了不同电池在电极涂层、颗粒大小和阴极材料方面的差异，这些差异又与电池的电学行为相关联。这凸显了保持钠离子电池性能的挑战，尤其是在低温条件下。这项研究旨在为钠离子电池技术的学术和工业研究建立一个全面的知识库。
{"title":"Comprehensive Analysis of Commercial Sodium-Ion Batteries: Structural and Electrochemical Insights","authors":"Filip Adam Dorau, Alessandro Sommer, Jan Koloch, Richard Röß-Ohlenroth, Markus Schreiber, Maximilian Neuner, Kareem Abo Gamra, Yilei Lin, Jan Schöberl, Philip Bilfinger, Sophie Grabmann, Benedikt Stumper, Leon Katzenmeier, Markus Lienkamp and Rüdiger Daub","doi":"10.1149/1945-7111/ad7765","DOIUrl":"https://doi.org/10.1149/1945-7111/ad7765","url":null,"abstract":"Considering the growing need for extensive energy storage solutions in smart grid technologies and affordable options for entry-level electric vehicles, sodium-ion batteries offer a promising alternative. They use raw materials that are cheaper, less toxic, and more abundant than those used in lithium-ion batteries, making them especially suitable for large-scale applications. This study comprehensively investigated four commercially available sodium-ion batteries to examine their structural and electrochemical characteristics. The cells were dissected, and the electrode dimensions, the areal mass loadings, and the material compositions were analyzed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, powder X-ray diffraction, and attenuated total reflection Fourier-transform infrared spectroscopy. Electrical characterization, including electrochemical impedance spectroscopy, C-rate testing up to 6 C under different ambient temperatures, along with cyclic aging studies, provided insights into the cells’ performance and degradation mechanisms. The findings highlighted variations in electrode coatings, particle sizes, and cathode materials among the cells, which were then correlated with their electrical behavior. This emphasized the challenges in maintaining sodium-ion battery performance, especially at low temperatures. This study was designed to establish a comprehensive knowledge base for both academic and industrial research in sodium-ion battery technology.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263381","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/ad7766
Roopa Margaret Rodrigues and Anitha Varghese
Electro-organic chemistry offers a sustainable and efficient approach to organic synthesis by utilizing electrochemical processes. This field has gained significant attention due to its potential for minimizing waste, reducing energy consumption, and enabling selective transformations. Herein, we report the development of a graphitic carbon nitride-coated carbon fiber electrode modified with electropolymerized amino-2-thiazole and electrodeposited Cu2O nanoparticles from copper nitrate trihydrate for the oxidation of Indole-3-carbinol (IC). Scanning electron microscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy studies were carried out to characterize the developed electrode. Cyclic voltammetry, electrochemical impedance spectroscopy, and bulk electrolysis techniques were employed for the electrochemical studies. The enhanced electrochemical activity of the Cu2O-pAT-GCN-TCFP electrode compared to the individual GCN and polymer electrode was studied using electrochemical characterization, which revealed a 3-fold increase in the current response for Cu2O-pAT-GCN-TCFP (0.0011 A) compared to the bare electrode. The reaction was carried out using an aqueous carbonate buffer solution as an electrolyte via bulk electrolysis at a set potential of 0.82 V. The product obtained was isolated by column chromatography to obtain a yield of 74% and characterized by proton nuclear magnetic resonance (1H NMR) spectroscopy. Additionally, the Cu2O-pAT-GCN-TCFP electrode was studied for its stability, reproducibility, and selectivity.
{"title":"Indole-3-Carbinol Upconversion with Copper Oxide Nanoparticles Supported Graphitic Carbon Nitride: A Sustainable Approach","authors":"Roopa Margaret Rodrigues and Anitha Varghese","doi":"10.1149/1945-7111/ad7766","DOIUrl":"https://doi.org/10.1149/1945-7111/ad7766","url":null,"abstract":"Electro-organic chemistry offers a sustainable and efficient approach to organic synthesis by utilizing electrochemical processes. This field has gained significant attention due to its potential for minimizing waste, reducing energy consumption, and enabling selective transformations. Herein, we report the development of a graphitic carbon nitride-coated carbon fiber electrode modified with electropolymerized amino-2-thiazole and electrodeposited Cu2O nanoparticles from copper nitrate trihydrate for the oxidation of Indole-3-carbinol (IC). Scanning electron microscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy studies were carried out to characterize the developed electrode. Cyclic voltammetry, electrochemical impedance spectroscopy, and bulk electrolysis techniques were employed for the electrochemical studies. The enhanced electrochemical activity of the Cu2O-pAT-GCN-TCFP electrode compared to the individual GCN and polymer electrode was studied using electrochemical characterization, which revealed a 3-fold increase in the current response for Cu2O-pAT-GCN-TCFP (0.0011 A) compared to the bare electrode. The reaction was carried out using an aqueous carbonate buffer solution as an electrolyte via bulk electrolysis at a set potential of 0.82 V. The product obtained was isolated by column chromatography to obtain a yield of 74% and characterized by proton nuclear magnetic resonance (1H NMR) spectroscopy. Additionally, the Cu2O-pAT-GCN-TCFP electrode was studied for its stability, reproducibility, and selectivity.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263386","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/ad77b1
Jean E. Marshall, Victoria White, Ke Zhang, Philip Bellchambers, Jerzy Gazda, Mark Copley, Louis F. J. Piper and Matthew J. Capener
This work presents 3-Methyl-2-oxazolidinone (JEFFSOL® MEOX) as a substitute solvent for N-methyl-2-pyrrolidone (NMP) in the manufacture of Li-ion batteries. NMP is a good solvent for polyvinylidene difluoride (PVDF, a common binder material), and also has a high boiling point (202 °C), allowing for gradual drying of electrode slurries to form homogeneous coatings. However, NMP has a reprotoxic effect and its use is attracting increasing legislative pressure; it would be advantageous to the battery-making industry to find a more benign alternative. Of the few other solvents that will readily dissolve PVDF, examples such as dimethylformamide are also significantly toxic, so further investigation is necessary to find a credible alternative solvent system. We show that JEFFSOL® MEOX (boiling point 225 °C) is capable of dissolving PVDF at accessible temperatures (40 °C–50 °C), and that at a similar ratio of active material:binder:solvent, both JEFFSOL® MEOX and NMP produce electrode slurries with a viscosity of 5–6 Pa.s at 25 °C and at a shear rate of 10 s−1. Cells formed using JEFFSOL® MEOX-made and NMP-made cathode coatings showed comparable electrochemical performance.
{"title":"3-Methyl-2-oxazolidinone (JEFFSOL® MEOX) as a Substitute Solvent for NMP in Battery Manufacturing","authors":"Jean E. Marshall, Victoria White, Ke Zhang, Philip Bellchambers, Jerzy Gazda, Mark Copley, Louis F. J. Piper and Matthew J. Capener","doi":"10.1149/1945-7111/ad77b1","DOIUrl":"https://doi.org/10.1149/1945-7111/ad77b1","url":null,"abstract":"This work presents 3-Methyl-2-oxazolidinone (JEFFSOL® MEOX) as a substitute solvent for N-methyl-2-pyrrolidone (NMP) in the manufacture of Li-ion batteries. NMP is a good solvent for polyvinylidene difluoride (PVDF, a common binder material), and also has a high boiling point (202 °C), allowing for gradual drying of electrode slurries to form homogeneous coatings. However, NMP has a reprotoxic effect and its use is attracting increasing legislative pressure; it would be advantageous to the battery-making industry to find a more benign alternative. Of the few other solvents that will readily dissolve PVDF, examples such as dimethylformamide are also significantly toxic, so further investigation is necessary to find a credible alternative solvent system. We show that JEFFSOL® MEOX (boiling point 225 °C) is capable of dissolving PVDF at accessible temperatures (40 °C–50 °C), and that at a similar ratio of active material:binder:solvent, both JEFFSOL® MEOX and NMP produce electrode slurries with a viscosity of 5–6 Pa.s at 25 °C and at a shear rate of 10 s−1. Cells formed using JEFFSOL® MEOX-made and NMP-made cathode coatings showed comparable electrochemical performance.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263644","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/ad790f
Kiem Do Van, Nguyen Van Hieu, Thomas C-K Yang and Tu Le Manh
Hydrogen sulfide (H2S) causes significant impacts on human health and the environment due to its highly toxic properties. Thus, the design and development of gas sensors to detect and monitor H2S (especially at extremely low concentrations) are challenging tasks for scientists. In this work, SnO2 gas sensors were successfully synthesized directly on a chip by Sn electrodeposition from ethylene glycol solutions + a post-treatment (calcination) stage (to form and stabilize SnO2). Mechanisms and kinetics of Sn electrodeposition on Pt microelectrodes were thoroughly studied using electrochemical techniques. These fabricated gas sensors exhibit a high selectivity toward H2S gas and an effective response to low-level concentrations of H2S in the range of 0.1 ppm–1 ppm at different working temperatures. The influence of electrodeposition conditions and calcination temperatures on the gas response of sensors were also examined. The results have verified that the electrodeposition method from ethylene glycol solutions is promising for the fabrication of ultrasensitive on-chip gas sensors.
{"title":"Rapid Detection of Ultralow H2S Concentration with on-chip Fabrication of SnO2-based Gas Sensors by Direct Electrodeposition from Non-Aqueous Solvents","authors":"Kiem Do Van, Nguyen Van Hieu, Thomas C-K Yang and Tu Le Manh","doi":"10.1149/1945-7111/ad790f","DOIUrl":"https://doi.org/10.1149/1945-7111/ad790f","url":null,"abstract":"Hydrogen sulfide (H2S) causes significant impacts on human health and the environment due to its highly toxic properties. Thus, the design and development of gas sensors to detect and monitor H2S (especially at extremely low concentrations) are challenging tasks for scientists. In this work, SnO2 gas sensors were successfully synthesized directly on a chip by Sn electrodeposition from ethylene glycol solutions + a post-treatment (calcination) stage (to form and stabilize SnO2). Mechanisms and kinetics of Sn electrodeposition on Pt microelectrodes were thoroughly studied using electrochemical techniques. These fabricated gas sensors exhibit a high selectivity toward H2S gas and an effective response to low-level concentrations of H2S in the range of 0.1 ppm–1 ppm at different working temperatures. The influence of electrodeposition conditions and calcination temperatures on the gas response of sensors were also examined. The results have verified that the electrodeposition method from ethylene glycol solutions is promising for the fabrication of ultrasensitive on-chip gas sensors.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263590","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/ad77f6
Mani Jayakumar, M. Karthikeyan, G. Murali Krishna and Chrysanthus Andrew
The electrochemical behaviour of nickel(II)-rhenium(VII) and the electrodeposition of nickel-rhenium alloy using choline chloride: 2 Urea deep eutectic solvent (Reline DES) is reported. Speciation of nickel(II)-rhenium(VII) in Reline DES was studied using UV -Visible spectroscopy. Cyclic voltammetry of Ni2+-ReO4− in Reline indicates the simultaneous reduction of two metal ions at glassy carbon electrode controlled by non-reversible diffusion process. Chronoamperograms obtained for the reduction of Ni2+-ReO4− suggests nucleation and three-dimensional growth of bimetallic phase on electrode surface followed progressive nucleation. Electrodeposition of nickel—rhenium alloy was carried out on copper substrates under galvanostatic and potentiostatic conditions. Smooth and uniform deposits were obtained by galvanostatic deposition. X-ray diffraction analysis of the deposit confirmed it to be nickel-rhenium alloy (at −1.2 V) in amorphous form which upon annealing at 1000 °C crystallizes into hexagonal phase with concurrent morphology change from spherical particles to irregular polygons.
报告了镍(II)-铼(VII)的电化学行为以及使用氯化胆碱：2 尿素深共晶溶剂（Reline DES）电沉积镍铼合金的情况。使用紫外可见光谱法研究了 Reline DES 中镍(II)-铼(VII)的种类。Ni2+-ReO4- 在 Reline 中的循环伏安法表明，两种金属离子在玻璃碳电极上同时还原，并受到非可逆扩散过程的控制。在还原 Ni2+-ReO4- 的过程中获得的计时器图表明，双金属相在电极表面逐渐成核并三维生长。在静电和恒电位条件下，在铜基底上进行了镍铼合金的电沉积。通过静电沉积获得了光滑均匀的沉积物。沉积物的 X 射线衍射分析表明，沉积物是无定形的镍铼合金（电压为 -1.2 V），在 1000 °C 退火后结晶成六方相，同时形态从球形颗粒变为不规则多边形。
{"title":"Electrochemical Behaviour of Nickel(II)-Rhenium(VII) And Electrodeposition of Nickel-Rhenium Alloy from Choline Chloride - Urea Deep Eutectic Solvent","authors":"Mani Jayakumar, M. Karthikeyan, G. Murali Krishna and Chrysanthus Andrew","doi":"10.1149/1945-7111/ad77f6","DOIUrl":"https://doi.org/10.1149/1945-7111/ad77f6","url":null,"abstract":"The electrochemical behaviour of nickel(II)-rhenium(VII) and the electrodeposition of nickel-rhenium alloy using choline chloride: 2 Urea deep eutectic solvent (Reline DES) is reported. Speciation of nickel(II)-rhenium(VII) in Reline DES was studied using UV -Visible spectroscopy. Cyclic voltammetry of Ni2+-ReO4− in Reline indicates the simultaneous reduction of two metal ions at glassy carbon electrode controlled by non-reversible diffusion process. Chronoamperograms obtained for the reduction of Ni2+-ReO4− suggests nucleation and three-dimensional growth of bimetallic phase on electrode surface followed progressive nucleation. Electrodeposition of nickel—rhenium alloy was carried out on copper substrates under galvanostatic and potentiostatic conditions. Smooth and uniform deposits were obtained by galvanostatic deposition. X-ray diffraction analysis of the deposit confirmed it to be nickel-rhenium alloy (at −1.2 V) in amorphous form which upon annealing at 1000 °C crystallizes into hexagonal phase with concurrent morphology change from spherical particles to irregular polygons.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263382","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/ad7983
Xueyuan Wei, Yao Liu and Lesi Wei
In this study, we examined the surface morphology and crystal structure of RF-sputtered ZnO thin films that were annealed at various temperatures. Also, we fabricated UV photodetectors with an Au-ZnO-ITO sandwich structure, utilizing the thin films annealed at 600 °C. The surface roughness of the film initially increases and then decreases as the annealing temperature rises, and the crystalline quality improves with an increase in the annealing temperature. Due to the Schottky heterojunction formed by the Au-semi contact, the fabricated UV photodetector exhibits a responsivity of 7.91 mA W−1 under 405 nm UV light. And the device demonstrates high response stability and rapid response sensitivity, with a swift rise time of 80 ms at a light intensity of 2.56 mW cm−2.
在这项研究中，我们考察了在不同温度下退火的射频溅射氧化锌薄膜的表面形貌和晶体结构。此外，我们还利用在 600 °C 下退火的薄膜制造了具有金-氧化锌-氧化钛夹层结构的紫外光检测器。随着退火温度的升高，薄膜的表面粗糙度先增大后减小，晶体质量也随着退火温度的升高而提高。由于金-半接触形成了肖特基异质结，因此所制备的紫外光探测器在 405 纳米紫外光下的响应率为 7.91 mA W-1。该器件具有高响应稳定性和快速响应灵敏度，在光强为 2.56 mW cm-2 时，快速上升时间为 80 ms。
{"title":"Optimization of Post-Annealing Temperature of RF Magnetron-Sputtered ZnO Thin Films for Enhancing Performances of UV Photodetectors","authors":"Xueyuan Wei, Yao Liu and Lesi Wei","doi":"10.1149/1945-7111/ad7983","DOIUrl":"https://doi.org/10.1149/1945-7111/ad7983","url":null,"abstract":"In this study, we examined the surface morphology and crystal structure of RF-sputtered ZnO thin films that were annealed at various temperatures. Also, we fabricated UV photodetectors with an Au-ZnO-ITO sandwich structure, utilizing the thin films annealed at 600 °C. The surface roughness of the film initially increases and then decreases as the annealing temperature rises, and the crystalline quality improves with an increase in the annealing temperature. Due to the Schottky heterojunction formed by the Au-semi contact, the fabricated UV photodetector exhibits a responsivity of 7.91 mA W−1 under 405 nm UV light. And the device demonstrates high response stability and rapid response sensitivity, with a swift rise time of 80 ms at a light intensity of 2.56 mW cm−2.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263384","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/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":null,"pages":null},"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":null,"pages":null},"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/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":null,"pages":null},"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/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":null,"pages":null},"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}
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