Pub Date : 2024-09-06DOI: 10.1149/1945-7111/ad6e1f
Saheli Bhattacharjee, Sovandeb Sen, Susmita Kundu
Vanadium pentoxide (V2O5), associated with both cathodic and anodic coloration, is considered as one of the best electrochromic (EC) materials for energy-saving smart electronics. Here we present the fabrication and detailed mechanism analysis for improving the electrochromic properties of V2O5 incorporated in a reduced graphene oxide (rGO) matrix using a facile wet chemical method. The microstructural study disclosed the formation of prominent V2O5 nanorods embedded in the rGO matrix. The optimized electrochromic film resulted in coloration (tc) and bleaching time (tb) of ∼6.2 and ∼4.8 s, respectively, much faster than the color switching kinetics of the pristine V2O5 sample (tc ∼ 19.4 s, tb ∼ 15.3 s). The more dispersed structure also ensured an approximate 400% enhancement in the optical modulation of EC film and reflected a noticeable improvement in the coloration efficiency (∼347 cm2/C) of V2O5 film. Modification with rGO resulted in an outstanding improvement in the electrochemical redox stability of V2O5 up to 5000 CV cycles with minimum deterioration in the curve area. The formation of nanorod structure was the prime factor for better ion diffusion and thereby facilitating enhanced performance.
{"title":"Robust Dual-Color Electrochromism of Vanadium Oxide Nanorods Embedded on Reduced Graphene Oxide: Unraveling the Mechanism","authors":"Saheli Bhattacharjee, Sovandeb Sen, Susmita Kundu","doi":"10.1149/1945-7111/ad6e1f","DOIUrl":"https://doi.org/10.1149/1945-7111/ad6e1f","url":null,"abstract":"Vanadium pentoxide (V<sub>2</sub>O<sub>5</sub>), associated with both cathodic and anodic coloration, is considered as one of the best electrochromic (EC) materials for energy-saving smart electronics. Here we present the fabrication and detailed mechanism analysis for improving the electrochromic properties of V<sub>2</sub>O<sub>5</sub> incorporated in a reduced graphene oxide (rGO) matrix using a facile wet chemical method. The microstructural study disclosed the formation of prominent V<sub>2</sub>O<sub>5</sub> nanorods embedded in the rGO matrix. The optimized electrochromic film resulted in coloration (t<sub>c</sub>) and bleaching time (t<sub>b</sub>) of ∼6.2 and ∼4.8 s, respectively, much faster than the color switching kinetics of the pristine V<sub>2</sub>O<sub>5</sub> sample (t<sub>c</sub> ∼ 19.4 s, t<sub>b</sub> ∼ 15.3 s). The more dispersed structure also ensured an approximate 400% enhancement in the optical modulation of EC film and reflected a noticeable improvement in the coloration efficiency (∼347 cm<sup>2</sup>/C) of V<sub>2</sub>O<sub>5</sub> film. Modification with rGO resulted in an outstanding improvement in the electrochemical redox stability of V<sub>2</sub>O<sub>5</sub> up to 5000 CV cycles with minimum deterioration in the curve area. The formation of nanorod structure was the prime factor for better ion diffusion and thereby facilitating enhanced performance.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"44 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222458","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 : 2024-09-06DOI: 10.1149/1945-7111/ad749e
Hunter Teel, Taylor R. Garrick, Brian J. Koch, Miguel A. Fernandez, Srikant Srinivasan, Fengkun Wang, Yangbing Zeng, Sirivatch Shimpalee
In this work, a 3D representation of a lithium ion electric vehicle battery cell was created and modeled through the discrete element method (DEM) to capture the porous electrode volume change during cell operation and its effects on electrode strain, porosity changes, and pressure generation for each electrode. This was coupled with a representative volume element approach and the multi species reaction model to quantify the impact of these changes at an electrode level have on the cell level operation. Results on both the electrode level and cell level response were discussed to give insights on how the volume changes contribute to both strain and porosity changes and the potential effects these changes have on the electrochemical response of the generated representative cells. Predictions on the cell level response, particularly for porosity changes which can be difficult to capture experimentally, are essential for the further development of high energy density cells that utilize unique chemistries prone to high levels of volume change such as silicon and silicon oxides. The ability to predict the active material volume change and its nuances will be informative and essential to rapidly develop and design cells for both automotive and grid storage applications.
{"title":"Utilization of DEM Simulations to Quantify Cell Level Thickness and Volume Changes in Large Format Pouch Cells","authors":"Hunter Teel, Taylor R. Garrick, Brian J. Koch, Miguel A. Fernandez, Srikant Srinivasan, Fengkun Wang, Yangbing Zeng, Sirivatch Shimpalee","doi":"10.1149/1945-7111/ad749e","DOIUrl":"https://doi.org/10.1149/1945-7111/ad749e","url":null,"abstract":"In this work, a 3D representation of a lithium ion electric vehicle battery cell was created and modeled through the discrete element method (DEM) to capture the porous electrode volume change during cell operation and its effects on electrode strain, porosity changes, and pressure generation for each electrode. This was coupled with a representative volume element approach and the multi species reaction model to quantify the impact of these changes at an electrode level have on the cell level operation. Results on both the electrode level and cell level response were discussed to give insights on how the volume changes contribute to both strain and porosity changes and the potential effects these changes have on the electrochemical response of the generated representative cells. Predictions on the cell level response, particularly for porosity changes which can be difficult to capture experimentally, are essential for the further development of high energy density cells that utilize unique chemistries prone to high levels of volume change such as silicon and silicon oxides. The ability to predict the active material volume change and its nuances will be informative and essential to rapidly develop and design cells for both automotive and grid storage applications.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"73 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222405","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 : 2024-09-05DOI: 10.1149/1945-7111/ad69c5
Zhichen Liu, Ying Li
Thermal runaway monitoring and analysis has become a serious challenge to the safety of lithium-ion battery driven electric equipment. Thermal-runaway monitoring is crucial to avoid the burning and explosion of lithium batteries. This paper proposes a new type of deep neural network, known as whole-feature neural networks (WFNN), for lithium battery thermal-runaway monitoring. The neural networks learn the thermal-runaway patterns of a lithium battery from the measured temperatures, current, and voltages. WFNN is an end-to-end model for thermal-runaway monitoring of lithium batteries. An experiment on thermal-runaway monitoring of lithium batteries was carried out to evaluate the performance of the proposed WFNN. The monitoring accuracy is up to 99.48%, which is higher than those of support vector machine, kernel support vector machine, k-nearest neighbor, and fully-connected neural networks. Moreover, the computation efficiency of WFNN is high enough for real-time thermal-runaway monitoring. As a result, experimental results show that the proposed WFNN is applicable to the thermal-runaway monitoring of lithium batteries.
{"title":"Lithium Battery Thermal-Runaway Monitoring Based on Whole-Feature Neural Networks","authors":"Zhichen Liu, Ying Li","doi":"10.1149/1945-7111/ad69c5","DOIUrl":"https://doi.org/10.1149/1945-7111/ad69c5","url":null,"abstract":"Thermal runaway monitoring and analysis has become a serious challenge to the safety of lithium-ion battery driven electric equipment. Thermal-runaway monitoring is crucial to avoid the burning and explosion of lithium batteries. This paper proposes a new type of deep neural network, known as whole-feature neural networks (WFNN), for lithium battery thermal-runaway monitoring. The neural networks learn the thermal-runaway patterns of a lithium battery from the measured temperatures, current, and voltages. WFNN is an end-to-end model for thermal-runaway monitoring of lithium batteries. An experiment on thermal-runaway monitoring of lithium batteries was carried out to evaluate the performance of the proposed WFNN. The monitoring accuracy is up to 99.48%, which is higher than those of support vector machine, kernel support vector machine, k-nearest neighbor, and fully-connected neural networks. Moreover, the computation efficiency of WFNN is high enough for real-time thermal-runaway monitoring. As a result, experimental results show that the proposed WFNN is applicable to the thermal-runaway monitoring of lithium batteries.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"62 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222406","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}
In this work, the effect of electrolysis modes and their parameters on the morphology of the silicon deposits on glassy carbon were studied. In direct current mode it was found that an increase in current density and deposition time changes the morphology of the silicon from a coating to a deposit with a complex surface. Scanning electron microscopy showed that silicon films produced at low current densities and a short deposition time are represented by spherical particles with a diameter of less than 1 μm. The pulse current mode made it possible to increase the cathode density of the deposition current, and the pulse current density to an average of ≈250 mA cm−2 does not lead to the formation of a large amount of dendritic deposit. It was found that a low frequency makes it possible to obtain higher-quality silicon coatings, because when the frequency increases, the coating most often does not cover the entire electrode. The high value of the duty cycle, even at low pulse current densities, always leads to the formation of dendrites. An increase in the total deposition time also leads to an increase in the amount of deposit and the formation of dendrites.
这项工作研究了电解模式及其参数对玻璃碳上硅沉积物形态的影响。研究发现，在直流电模式下，电流密度和沉积时间的增加会改变硅的形态，使其从涂层变为表面复杂的沉积物。扫描电子显微镜显示，在低电流密度和短沉积时间下产生的硅薄膜是直径小于 1 μm 的球形颗粒。脉冲电流模式可以提高沉积电流的阴极密度，平均≈250 mA cm-2的脉冲电流密度不会导致形成大量树枝状沉积物。研究发现，低频率可以获得更高质量的硅涂层，因为当频率增加时，涂层往往无法覆盖整个电极。即使在低脉冲电流密度下，高占空比也会导致树枝状沉积的形成。总沉积时间的增加也会导致沉积量的增加和树枝状晶粒的形成。
{"title":"Electrodeposition of Silicon in the Low-Temperature LiCl-KCl-CsCl-K2SiF6 Melt Under Direct and Pulse Current","authors":"Yulia Parasotchenko, Andrey Suzdaltsev, Yuriy Zaykov","doi":"10.1149/1945-7111/ad73a8","DOIUrl":"https://doi.org/10.1149/1945-7111/ad73a8","url":null,"abstract":"In this work, the effect of electrolysis modes and their parameters on the morphology of the silicon deposits on glassy carbon were studied. In direct current mode it was found that an increase in current density and deposition time changes the morphology of the silicon from a coating to a deposit with a complex surface. Scanning electron microscopy showed that silicon films produced at low current densities and a short deposition time are represented by spherical particles with a diameter of less than 1 μm. The pulse current mode made it possible to increase the cathode density of the deposition current, and the pulse current density to an average of ≈250 mA cm<sup>−2</sup> does not lead to the formation of a large amount of dendritic deposit. It was found that a low frequency makes it possible to obtain higher-quality silicon coatings, because when the frequency increases, the coating most often does not cover the entire electrode. The high value of the duty cycle, even at low pulse current densities, always leads to the formation of dendrites. An increase in the total deposition time also leads to an increase in the amount of deposit and the formation of dendrites.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"45 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222409","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}
Porous Al particles with etching pits on their surfaces were prepared by anode etching using a rotating barrel. In this process, Al particles were placed in a barrel with a Pt plate electrode at the bottom. The Al particles were electrified by contacting the Pt electrode in the rotating barrel, and anode etching occurred on the surfaces of the Al particles. The structure of the etching pits formed on the surfaces of the Al particles could be controlled by adjusting the current and electrolysis time during the barrel anode etching. In addition, using an electrolyte solution with a surfactant, it was possible to form etching pits even on the surfaces of Al particles with sizes of 5 μm or less. Porous Mg particles could also be prepared by barrel anode etching using fine Mg particles as the starting material. The porous metal particles obtained using this process have a wide range of potential applications, including sensors, catalyst carriers, and batteries.
{"title":"Fabrication of Porous Metal Particles with Controlled Surface Structures by Barrel Anode Etching","authors":"Takashi Yanagishita, Shota Ueno, Toshiaki Kondo, Hideki Masuda","doi":"10.1149/1945-7111/ad73a9","DOIUrl":"https://doi.org/10.1149/1945-7111/ad73a9","url":null,"abstract":"Porous Al particles with etching pits on their surfaces were prepared by anode etching using a rotating barrel. In this process, Al particles were placed in a barrel with a Pt plate electrode at the bottom. The Al particles were electrified by contacting the Pt electrode in the rotating barrel, and anode etching occurred on the surfaces of the Al particles. The structure of the etching pits formed on the surfaces of the Al particles could be controlled by adjusting the current and electrolysis time during the barrel anode etching. In addition, using an electrolyte solution with a surfactant, it was possible to form etching pits even on the surfaces of Al particles with sizes of 5 μm or less. Porous Mg particles could also be prepared by barrel anode etching using fine Mg particles as the starting material. The porous metal particles obtained using this process have a wide range of potential applications, including sensors, catalyst carriers, and batteries.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"9 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222427","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}
We designed a bi-metallic Co-Ni/BTC/4,4′-BiPy metal organic frameworks (MOFs) as an electrode material for the electrochemical detection of epinephrine and nor-epinephrine. The bi-metallic MOFs were synthesized by a solvothermal method. Following this, the bimetallic MOFs were modified with BTC and amine rich 4,4′-BiPy to improve charge transfer kinetics through non-covalent π–π interaction. This modified electrode was employed as a sensing platform for the simultaneous electrochemical detection of epinephrine and nor-epinephrine. The MOFs modified platform exhibited a 10–50 μM linear range with a limit of detection of 0.724 μM ± 0.128 (N = 3) and 0.815 μM ± 0.124 (N = 3), a sensitivity of 0.583 and 0.505 μA μM−1 cm−2 corresponding to epinephrine and nor-epinephrine detection. Finally, the electrochemical sensor was tested in blood and urine samples spiked with known concentrations of epinephrine and nor-epinephrine. Results confirmed the usefulness of the proposed platform for the detection of epinephrine and nor-epinephrine in clinical samples.
{"title":"Bimetallic MOFs-Based Electrodes for the Simultaneous Electrochemical Detection of Epinephrine and Nor-Epinephrine","authors":"Charlin Soosaimanickam, Kathiresan Murugavel, Subbiah Alwarappan","doi":"10.1149/1945-7111/ad6c80","DOIUrl":"https://doi.org/10.1149/1945-7111/ad6c80","url":null,"abstract":"We designed a bi-metallic Co-Ni/BTC/4,4′-BiPy metal organic frameworks (MOFs) as an electrode material for the electrochemical detection of epinephrine and nor-epinephrine. The bi-metallic MOFs were synthesized by a solvothermal method. Following this, the bimetallic MOFs were modified with BTC and amine rich 4,4′-BiPy to improve charge transfer kinetics through non-covalent <italic toggle=\"yes\">π</italic>–<italic toggle=\"yes\">π</italic> interaction. This modified electrode was employed as a sensing platform for the simultaneous electrochemical detection of epinephrine and nor-epinephrine. The MOFs modified platform exhibited a 10–50 μM linear range with a limit of detection of 0.724 μM ± 0.128 (N = 3) and 0.815 μM ± 0.124 (N = 3), a sensitivity of 0.583 and 0.505 μA μM<sup>−1</sup> cm<sup>−2</sup> corresponding to epinephrine and nor-epinephrine detection. Finally, the electrochemical sensor was tested in blood and urine samples spiked with known concentrations of epinephrine and nor-epinephrine. Results confirmed the usefulness of the proposed platform for the detection of epinephrine and nor-epinephrine in clinical samples.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"10 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222431","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 : 2024-09-04DOI: 10.1149/1945-7111/ad7326
Ryosuke Jinnouchi
This article introduces the first principles-based grand-canonical formalisms of several representative electronic structure calculation methods in electrochemistry, which are essential for elucidating the atomic-scale mechanisms of electrochemical reactions and discovering the guiding principles for designing advanced materials. While most applications still rely on approximate structures obtained by static calculations at absolute zero, the foundational theories of more rigorous molecular dynamics simulations are also developing. I discuss methods that combine these theories with emerging machine-learning interatomic potentials, suggesting that this approach could pave the way to predict the thermodynamics and kinetics of electrochemical reactions at finite temperatures purely from first principles.
{"title":"Grand-Canonical First Principles-Based Calculations of Electrochemical Reactions","authors":"Ryosuke Jinnouchi","doi":"10.1149/1945-7111/ad7326","DOIUrl":"https://doi.org/10.1149/1945-7111/ad7326","url":null,"abstract":"This article introduces the first principles-based grand-canonical formalisms of several representative electronic structure calculation methods in electrochemistry, which are essential for elucidating the atomic-scale mechanisms of electrochemical reactions and discovering the guiding principles for designing advanced materials. While most applications still rely on approximate structures obtained by static calculations at absolute zero, the foundational theories of more rigorous molecular dynamics simulations are also developing. I discuss methods that combine these theories with emerging machine-learning interatomic potentials, suggesting that this approach could pave the way to predict the thermodynamics and kinetics of electrochemical reactions at finite temperatures purely from first principles.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"99 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222425","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 : 2024-09-04DOI: 10.1149/1945-7111/ad6e1d
Divya Deep Yadav, Ajay Kumar, Ranjana Jha, Sukhvir Singh
In the present work, a simple and effective hydrothermal method has been used to synthesize a nanocomposite of nickel oxide and molybdenum disulphide. Structural and optical characterizations of the as-synthesised MoS2/NiO nanocomposite nanoparticles were carried out using X-ray diffraction (XRD) and UV-visible spectroscopy techniques. The major peaks of MoS2 and NiO were detected in XRD, confirming the formation of a composite. The reduced band gap of 2.84 eV of MoS2/NiO nanocomposite, as compared to pure NiO with a 3.1 eV bandgap, indicates a blue shift. The surface morphology of MoS2/NiO nanocomposite was measured using field-emission scanning electron microscopy, showing a sheet-like structure with fine particles overlaid on them. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were used to determine the processes of charge transfer between electrodes, diffusion of molecules and ions within the electrolyte solution, and ion adsorption on the surface of the the electrode. The as-prepared composite shows an enhanced specific capacitance of 246 F g−1 at20 mV sec−1, a scan rate of which was more than both base materials in pristine form. EIS results thus obtained may give a new direction for supercapacitor applications with the as-synthesized sample.
本研究采用简单有效的水热法合成了氧化镍和二硫化钼的纳米复合材料。利用 X 射线衍射 (XRD) 和紫外可见光谱技术对合成的 MoS2/NiO 纳米复合纳米粒子进行了结构和光学表征。在 XRD 中检测到了 MoS2 和 NiO 的主要峰值，证实了复合材料的形成。与带隙为 3.1 eV 的纯 NiO 相比，MoS2/NiO 纳米复合材料的带隙减小到 2.84 eV，表明发生了蓝移。使用场发射扫描电子显微镜测量了 MoS2/NiO 纳米复合材料的表面形貌，结果表明其呈片状结构，上面叠加有细小颗粒。循环伏安法和电化学阻抗谱（EIS）用于确定电极间的电荷转移、电解质溶液中分子和离子的扩散以及电极表面的离子吸附过程。制备的复合材料在 20 mV sec-1 时的比电容为 246 F g-1，扫描速率高于两种原始形式的基底材料。由此获得的 EIS 结果可能会为合成样品的超级电容器应用提供一个新的方向。
{"title":"Flexible Ni-Foam-Based Electrode with Novel MoS2/NiO Nanocomposite for Superior Supercapacitor Applications","authors":"Divya Deep Yadav, Ajay Kumar, Ranjana Jha, Sukhvir Singh","doi":"10.1149/1945-7111/ad6e1d","DOIUrl":"https://doi.org/10.1149/1945-7111/ad6e1d","url":null,"abstract":"In the present work, a simple and effective hydrothermal method has been used to synthesize a nanocomposite of nickel oxide and molybdenum disulphide. Structural and optical characterizations of the as-synthesised MoS<sub>2</sub>/NiO nanocomposite nanoparticles were carried out using X-ray diffraction (XRD) and UV-visible spectroscopy techniques. The major peaks of MoS<sub>2</sub> and NiO were detected in XRD, confirming the formation of a composite. The reduced band gap of 2.84 eV of MoS2/NiO nanocomposite, as compared to pure NiO with a 3.1 eV bandgap, indicates a blue shift. The surface morphology of MoS2/NiO nanocomposite was measured using field-emission scanning electron microscopy, showing a sheet-like structure with fine particles overlaid on them. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were used to determine the processes of charge transfer between electrodes, diffusion of molecules and ions within the electrolyte solution, and ion adsorption on the surface of the the electrode. The as-prepared composite shows an enhanced specific capacitance of 246 F g−1 at20 mV sec−1, a scan rate of which was more than both base materials in pristine form. EIS results thus obtained may give a new direction for supercapacitor applications with the as-synthesized sample.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"3 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222407","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 : 2024-09-04DOI: 10.1149/1945-7111/ad71f9
Shunsuke Tomita, Tatsuya Kikuchi
The electropolishing behavior of pure magnesium and its alloys in ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TrEG), and tetraethylene glycol (TeEG) solutions containing sodium chloride was investigated using electrochemical measurements, microscopic observations, and reflectance measurements. Large light-grayish cloudy areas with micrometer-scale linear irregularities were formed on the magnesium surface via constant-voltage electrolysis in the EG solution, whereas mirror-finished magnesium surfaces were successfully obtained in the DEG and TeEG solutions. Among these, the DEG solution is considered appropriate for electropolishing because of its lower viscosity and market price. The reflectance of the entire visible wavelength region gradually increased with time during electrolysis in the DEG solution at 308 K. We found that short-term electrolysis for 3 min at the higher voltage of 75 V should be selected if a moderately polished surface is to be rapidly obtained, whereas long-term electrolysis for 60–300 min at 50 V should be performed if a highly polished surface with an extremely high reflectivity measuring more than 80% can be obtained. Three-dimensional magnesium specimens with curved and spiral shapes and an LZ91 magnesium alloy consisting of a simple solid-solution matrix can also be electropolished via electrolysis in a DEG solution.
通过电化学测量、显微镜观察和反射率测量，研究了纯镁及其合金在含氯化钠的乙二醇（EG）、二甘醇（DEG）、三甘醇（TrEG）和四甘醇（TeEG）溶液中的电解抛光行为。在 EG 溶液中通过恒压电解，镁表面形成了大面积浅灰色浑浊区，并伴有微米级的线性不规则，而在 DEG 和 TeEG 溶液中则成功获得了镜面镁表面。其中，DEG 溶液因其较低的粘度和市场价格而被认为适合电解抛光。在 308 K 的 DEG 溶液中进行电解时，整个可见光波长区域的反射率随着时间的推移逐渐增加。我们发现，如果要快速获得中等抛光的表面，应选择在 75 V 的较高电压下进行 3 分钟的短期电解，而如果要获得反射率超过 80% 的高抛光表面，则应在 50 V 的电压下进行 60-300 分钟的长期电解。具有弯曲和螺旋形状的三维镁试样以及由简单固溶体基质组成的 LZ91 镁合金也可以通过在 DEG 溶液中电解进行电抛光。
{"title":"Electropolishing of Magnesium and Its Alloys Using a Safe Glycol Solution Containing Sodium Chloride","authors":"Shunsuke Tomita, Tatsuya Kikuchi","doi":"10.1149/1945-7111/ad71f9","DOIUrl":"https://doi.org/10.1149/1945-7111/ad71f9","url":null,"abstract":"The electropolishing behavior of pure magnesium and its alloys in ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TrEG), and tetraethylene glycol (TeEG) solutions containing sodium chloride was investigated using electrochemical measurements, microscopic observations, and reflectance measurements. Large light-grayish cloudy areas with micrometer-scale linear irregularities were formed on the magnesium surface via constant-voltage electrolysis in the EG solution, whereas mirror-finished magnesium surfaces were successfully obtained in the DEG and TeEG solutions. Among these, the DEG solution is considered appropriate for electropolishing because of its lower viscosity and market price. The reflectance of the entire visible wavelength region gradually increased with time during electrolysis in the DEG solution at 308 K. We found that short-term electrolysis for 3 min at the higher voltage of 75 V should be selected if a moderately polished surface is to be rapidly obtained, whereas long-term electrolysis for 60–300 min at 50 V should be performed if a highly polished surface with an extremely high reflectivity measuring more than 80% can be obtained. Three-dimensional magnesium specimens with curved and spiral shapes and an LZ91 magnesium alloy consisting of a simple solid-solution matrix can also be electropolished via electrolysis in a DEG solution.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"26 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222408","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 : 2024-09-04DOI: 10.1149/1945-7111/ad7291
Xinsheng Wu, Jay F. Whitacre
P2-phased layered oxide materials have been extensively studied as cathode material for sodium-ion batteries due to their high capacities and ionic conductivities, making them promising for large-scale applications. Additionally, manganese-based compounds, with their low cost and high capacity, have attracted significant attention in recent years. However, challenges remain regarding durability issues and related structural instability caused by the Jahn-Teller effect induced by Mn3+ ions formed during the cycling process in these materials, which causes manganese dissolution during use. In this study, we introduce a cathode composition of Na0.8Mn0.75Fe0.2Al0.05O2 and show that bismuth doping enhances the structural stability of the cathode material during electrochemical cycling. Electrodes with varying levels of bismuth doping were compared in half-cell configurations; material with 1% bismuth doping demonstrated outstanding stability, retaining 95.8% capacity after 200 cycles at a 0.2 C rate through the full potential range. dQ/dV analysis shows that bismuth doping effectively suppresses the excess Mn redox, which could otherwise deteriorate the cathode structure. As a proof of concept, Bi-doped materials were implemented in full cells paired with hard carbon that exhibited much better stability than those without bismuth doping. Lastly, the moisture and air stability of the bismuth-doped electrode were tested, demonstrating good stability.
{"title":"Bi-Doped P2 layered Sodium-Ion Battery Cathode with Improved Cycling Stability","authors":"Xinsheng Wu, Jay F. Whitacre","doi":"10.1149/1945-7111/ad7291","DOIUrl":"https://doi.org/10.1149/1945-7111/ad7291","url":null,"abstract":"P2-phased layered oxide materials have been extensively studied as cathode material for sodium-ion batteries due to their high capacities and ionic conductivities, making them promising for large-scale applications. Additionally, manganese-based compounds, with their low cost and high capacity, have attracted significant attention in recent years. However, challenges remain regarding durability issues and related structural instability caused by the Jahn-Teller effect induced by Mn<sup>3+</sup> ions formed during the cycling process in these materials, which causes manganese dissolution during use. In this study, we introduce a cathode composition of Na<sub>0.8</sub>Mn<sub>0.75</sub>Fe<sub>0.2</sub>Al<sub>0.05</sub>O<sub>2</sub> and show that bismuth doping enhances the structural stability of the cathode material during electrochemical cycling. Electrodes with varying levels of bismuth doping were compared in half-cell configurations; material with 1% bismuth doping demonstrated outstanding stability, retaining 95.8% capacity after 200 cycles at a 0.2 C rate through the full potential range. dQ/dV analysis shows that bismuth doping effectively suppresses the excess Mn redox, which could otherwise deteriorate the cathode structure. As a proof of concept, Bi-doped materials were implemented in full cells paired with hard carbon that exhibited much better stability than those without bismuth doping. Lastly, the moisture and air stability of the bismuth-doped electrode were tested, demonstrating good stability.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"9 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222410","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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