Elucidating the transport of electrons and molecules in a solid electrolyte interphase close to battery operation potentials using a four-electrode-based generator-collector setup. - In: Journal of the American Chemical Society, ISSN 1520-5126, Bd. 146 (2024), 28, S. 19009-19018
In lithium-ion batteries, the solid electrolyte interphase (SEI) passivates the anode against reductive decomposition of the electrolyte but allows for electron transfer reactions between anode and redox shuttle molecules, which are added to the electrolyte as an internal overcharge protection. In order to elucidate the origin of these poorly understood passivation properties of the SEI with regard to different molecules, we used a four-electrode-based generator-collector setup to distinguish between electrolyte reduction current and the redox molecule (ferrocenium ion Fc+) reduction current at an SEI-covered glassy carbon electrode. The experiments were carried out in situ during potentiostatic SEI formation close to battery operation potentials. The measured generator and collector currents were used to calculate passivation factors of the SEI with regard to electrolyte reduction and with regard to Fc+ reduction. These passivation factors show huge differences in their absolute values and in their temporal evolution. By making simple assumptions about molecule transport, electron transport, and charge transfer reaction rates in the SEI, distinct passivation mechanisms are identified, strong indication is found for a transition during SEI growth from redox molecule reduction at the electrode | SEI interface to reduction at the SEI | electrolyte interface, and good estimates for the transport coefficients of both electrons and redox molecules are derived. The approach presented here is applicable to any type of electrochemical interphase and should thus also be of interest for interphase characterization in the fields of electrocatalysis and corrosion.
https://doi.org/10.1021/jacs.4c03029
Simulation of heat transfer and propagation velocity for different heat loss conditions for guided propagation fronts in reactive multilayer foils. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, 2400523, S. 1-9
Engineering self-propagating reactions in reactive material systems requires an understanding of critical ignition and propagation conditions. These conditions are governed by the material properties of the reactive materials responsible for net heat generation, as well as by external environmental conditions that primarily determine net heat loss. In this study, it is aimed to utilize a numerical model to investigate the critical conditions for reaction propagation based solely on the heat-transfer equation, enabling thorough examination with significantly low computational effort. Comparing simulations with experiments demonstrates a high level of agreement in predicting reaction propagation. Additionally, this numerical model provides valuable information regarding heat distribution in substrate materials.
https://doi.org/10.1002/adem.202400523
A bright future for electrodeposition. - In: The Electrochemical Society interface, ISSN 1944-8783, Bd. 33 (2024), 2, S. 45-46
The Electrodeposition Division, which was founded in 1922 as the second ECS division, celebrated their centennial anniversary at the 242nd ECS Fall meeting in Atlanta. For the occasion, the division organized several sessions with invited contributions to honor the achievements of 100 years of electrodeposition, but also to take a closer look at the present trendsetters and give a perspective on future challenges and opportunities in this thriving field. Our then newly established Electrodeposition Early Career Forum (ECF, founded in Spring 2022) organized a full day symposium with contributions from outstanding early-career researchers involved in cutting-edge research across a broad range of areas of active electrodeposition research. It turned out to be a fantastic day with invigorating talks full of ideas. The ELDP division decided to share some of the excitement with the ECS community and asked our ECF members to suggest topics and participate in the articles for this summer edition of Interface dedicated to Electrochemical and Electroless deposition. Dr. Kent Zheng, assistant professor at the University of Texas and Dr. Martin Leimbach, postdoc at TU Ilmenau, Germany, took up the challenge. Together with us, humble guest editors, four articles have been selected centred around three important topics: (1) electrodeposition for manufacturing and sustainability, edited by Prof. Luca Magagnin; (2) electrodeposition for energy applications, edited by Prof. Natasa Vasiljevic; and (3) new electrodeposition approaches extending the material library, edited by Prof. Philippe Vereecken.
https://doi.org/10.1149/2.F08242IF
Advancements in electrodeposition for precise manufacturing and sustainability. - In: The Electrochemical Society interface, ISSN 1944-8783, Bd. 33 (2024), 2, S. 47-54
Simply expressed, the circular economy implies that the people living on Earth should reuse and recycle the products that are currently in use as long as possible and reduce the waste produced, thus reducing CO2 emissions. The latter goal is fundamental from the perspective of mitigating the well-known greenhouse effect and the consequent global warming observed at the planetary scale. Under these conditions, advanced electrodeposition processes can play a fundamental role in the optimization of materials use and in the reduction of the energetic footprint for a wide variety of industrial processes. The aim of the present paper is precisely to suggest how this is possible, showing readers the potential that electrodeposition holds for efficient manufacturing of many different products that have a huge significance for industry.
https://doi.org/10.1149/2.F09242IF
Efficient tuning of the selectivity of Cu-based interface for electrocatalytic CO2 reduction by ligand modification. - In: Materials today, ISSN 2468-6069, Bd. 44 (2024), 101620, S. 1-12
The development of efficient strategies to tune the CO2RR selectivity of Cu-based catalytic interfaces, especially on specific domains, such as Cu (200) facets with high activity toward competitive hydrogenation evolution reaction (HER), remains a challenging task. In this work, Cu-based catalytic layers with thiocyanate (-SCN), cyanide (-CN), or ethylenediamine (-NH2R) coordination linkages are prepared on Cu nanocolumns arrays (Cu NCAs) with predominant (200) exposed facets. The coordination of these ligands induces more Cu+ species and inhibits the adsorption of H∗ on the Cu (200) facet, leading to enhanced CO2RR performance and substantially suppressing the competitive HER. The faradaic efficiency (FE) of Cu–SCN, Cu–CN, and Cu–NH2R NWAs for producing HCOOH, C2H4, and C1 mixture products (HCOOH and CO) reach to 66.5%, 21.1%, and 57.1%, respectively. In situ spectroscopic studies reveal Cu–SCN, Cu–CN, and Cu–NH2R exhibit more reasonable adsorption energy toward ∗OCHO, ∗CO, and ∗COOH intermediates, promoting the HCOOH, C2H4, and C1 mixture generation, respectively. This study might provide a new perspective for the development of high-performance Cu-based CO2RR catalytic electrodes based on the combination of various commercial free-standing Cu substrates and organic/inorganic ligands.
https://doi.org/10.1016/j.mtener.2024.101620
Influence of additional intermediate thick Al layers on the reaction propagation and heat flow of Al/Ni reactive multilayers. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, 2400522, S. 1-8
This study investigates the effects of sputtering and electron beam evaporation (e-beam) on the microstructure and reactive properties of Al/Ni reactive multilayers (RMLs). The intermixing zone, a critical factor influencing reaction kinetics, is characterized using high-resolution transmission electron microscopy and found to be consistently 3 nm for both fabrication methods. Differential scanning calorimetry reveals that e-beam samples, with thicker Al layers, exhibit slightly higher total molar enthalpy and maintain high reaction temperatures despite reduced reaction velocities in comparison to sputtered samples. X-ray diffraction confirms the formation of both Al3Ni2 and AlNi phases in the e-beam samples. These findings indicate that while thicker bilayer structures reduce reaction velocity, they keep thermal output and mitigate the impact of intermixing zones, leading to similar total molar enthalpy. This analysis underscores the significance of deposition technique and bilayer thickness in optimizing the performance of Al/Ni RML, offering the possibility to establish different phase formations in thicker RML. It advances the control over the reactive properties of RMLs in their applications, for example, reactive bonding.
https://doi.org/10.1002/adem.202400522
Transfer of self-sustained reactions between thermally coupled reactive material elements. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, 2400870, S. 1-14
System engineering requires the implementation of assembly methods allowing the formation of functional elements according to a desired system design. This is possible by joining prefabricated elements on a desired place in the system or by forming functional materials at wanted locations. Both approaches need temperature treatment. A typical system in part consists of materials restricting the use of annealing procedures above 300 ˚C. For this reason, higher-temperature operations have to be localized to the point of use and transferred to the next reactive element. A further requirement is the reduction of the thermal budget of the localized joining process implementing ultrashort heat treatment operations. Reactive metallic multilayer offers the combined possibility of implementing a localized heat source and the formation of a functional intermetallic alloy. The article demonstrates the feasibility of a heat and reaction transfer chain in a topological structured pattern consisting of localized reactive multilayer materials under conditions of their gasless combustion. For the used Ni/Al multilayer material system, the critical (obstacle thickness) dimensions for the reaction and heat transfer are determined using a high-speed camera and pyrometer measurements.
https://doi.org/10.1002/adem.202400870
The effect of zinc substitution on the optical properties of Sm3+ doped zinc borate glasses. - In: Optical materials, ISSN 1873-1252, Bd. 154 (2024), 115606, S. 1-19
Zinc borate glasses are a relatively well known glass type that can be produced at comparably low temperatures. Variations in both the type and concentration of network modifier atoms induce structural alterations within the glass matrix. If doped with optically active dopants, e.g. rare earth ions, compositional changes also affect the local surrounding of the dopants and consequently their optical properties such as emission peak shape and peak ratio. To investigate the effect of different low field strength network modifier ions in zinc borate glasses two glass series were prepared using the melt quench technique; Sm3+ was used as dopant ion: 50B2O3, xK2O, (49-x)ZnO, 1Sm2O3 (x = 5,10,15, …, 30 mol%) and 50B2O3, 30MO, 19ZnO, 1Sm2O3 (M = Ca, Sr and Ba). It is found that the substitution of ZnO for K2O notably enhances the intensity of the red Sm3+emission. Based on the literature this effect is attributed to a change in symmetry at the rare earth position. Additionally, the effect of network modifier concentrations and the different network modifier types on the Sm3+ absorption spectra is examined, discussed and compared to literature data. Furthermore, the glasses are characterized according to their density, refractive index, molar volume, and oxygen packing density.
https://doi.org/10.1016/j.optmat.2024.115606
Effects of N2 plasma modification on the surface properties and electrochemical performance of Ni foam electrodes for double-chamber microbial fuel cells. - In: Materials advances, ISSN 2633-5409, Bd. 5 (2024), 13, S. 5554-5560
This study assessed the feasibility of using a plasma-modified Ni foam as an anode to improve the electrochemical performance of double-chamber microbial fuel cells (MFCs). Scanning electron microscopy results showed that Ni foam exhibited an open cellular structure and rough surface morphology, providing a large contact area between bacteria and anodes in the MFCs. N2 plasma modification did not influence the surface morphology of the Ni foam, whereas the hydrophobic surfaces of the Ni foam became highly hydrophilic. X-ray photoelectron spectrometer results revealed that Ni-N and NH3 functional groups, formed on the surface of the Ni foam during the N2 plasma modification, were responsible for its highly hydrophilic surface. Electrochemical measurements demonstrated that the highest power density of the MFC configured with an unmodified Ni foam anode electrode (166.9 mW m−2) was much higher than those of the MFCs configured with dense Ni rod (5.1 mW m−2) or graphite rod (29.5 mW m−2) anodes because Ni foam combined the advantages of an open cellular structure and good electrical conductivity. The highest power density of MFC configured with Ni foam was further improved to 247.1 mW m−2 after 60 min N2 plasma treatment owing to the high hydrophilicity of the N2 plasma-modified Ni foam electrodes, which facilitated bacteria adhesion and biofilm formation.
https://doi.org/10.1039/D4MA00153B
Controlling propagation velocity in Al/Ni reactive multilayer systems by periodic 2D surface structuring. - In: Advanced engineering materials, ISSN 1527-2648, Bd. n/a (2024), n/a, 2302272, S. 1-11
The chemical energy released as heat during the exothermic reaction of reactive multilayer systems has shown potential applications in various technological areas, e.g., in joining applications. However, controlling the heat release rate and the propagation velocity of the reaction is required to enhance their performance in most of these applications. Herein, a method to control the propagation velocity and heat release rate of the system is presented. The sputtering of Al/Ni multilayers on substrates with periodic 2D surface structures promotes the formation of growth defects into the system. This modification in the morphology locally influences the reaction characteristics. Tailoring the number of 2D structures in the substrate enables the control of the velocity and maximum temperature of the propagation front. The morphology of the produced reactive multilayers is investigated before and after reaction using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. In addition, the enthalpy of the system is obtained through calorimetric analysis. The self-sustained and self-propagating reaction of the systems is monitored by a high-speed camera and a high-speed pyrometer, thus revealing the propagation velocity and the temperatures with time resolution in the microsecond regime.
https://doi.org/10.1002/adem.202302272