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Lithium isotope fractionation as a diagnostic tool for aging lithium-ion batteries
No full textLithium-ion batteries (LIBs) are central to modern energy storage technologies, powering applications from portable electronics to electric vehicles and grid storage systems. Their popularity comes from their high energy density, efficiency, and extended cycle life. However, over time, various aging mechanisms lead to capacity loss, increased internal resistance, and, ultimately, battery failure. Understanding and predicting these aging processes is crucial for enhancing the reliability and longevity of LIBs. This necessity makes the development of advanced diagnostic tools essential.
This study uses plasma-based spectrometry techniques to explore lithium isotope fractionation (LIF) as a predictive tool for monitoring LIB aging and degradation. Mass spectrometric techniques —including MC-ICP-MS, LA-ICP-MS, and MICAP-MS— were employed to analyze lithium isotopic composition in both new and aged lithium cobalt oxide (LCO) cells, including lab-made coin cells and commercial batteries.
An isotopic fractionation was identified during electrochemical cycling: 6Li migrates towards the anode, while 7Li accumulates in the cathode. These isotopic patterns correlate with structural degradation, including solid electrolyte interphase (SEI) growth and crack formation, as confirmed by FIB-SEM, XANES, and EXAFS analyses. This correlation demonstrates that LIF aligns with key aging mechanisms in model coin cells and commercial batteries, such as capacity fade and impedance growth. LIF provides a powerful diagnostic tool for battery health monitoring and aging prediction by linking isotopic fractionation to structural degradation. This approach offers significant potential to extend battery lifespan and improve the reliability of energy storage systems
Hyphenated Electrochemistry Mass Spectrometry (EC MS): A Powerful Tool for Investigating the Environmental Fate of Emerging Contaminants
No full textElectrochemistry coupled to mass spectrometry (EC-MS) is emerging as a powerful and versatile technique for studying chemical transformations in various fields. This communication provides an overview of recent advances in EC-MS, focusing on its applications in drug metabolism studies, environmental degradation of xenobiotics, and green synthesis of analytical standards. EC-MS offers significant advantages over conventional methods, including in situ simulation of metabolic and environmental processes, rapid generation of transformation products, and the possibility of performing milligram-scale syntheses with a reduced environmental footprint. The major contributions of leading equipment manufacturers, such as Antec Scientific for electrochemistry and Agilent, Shimadzu, Thermo Fisher Scientific, Bruker, Waters, and Sciex for mass spectrometry, will be highlighted. Finally, a portion of our work on the ecotoxicity study of neonicotinoid pesticides, using EC-MS, will be presented to illustrate the potential of this technique. Our study investigates the formation of degradation products from electrochemical reactors (EC) for neonicotinoid insecticides and phenylurea herbicides
upMIN 100 – upcycling of mineral construction and demolition waste to substitute natural aggregates in earthen building materials
No full textThe construction sector is one of the most resource-intensive sectors in Germany and is responsible for 40 % of CO2 emissions. emissions. Around 517 million tons of mineral raw materials are required annually for the construction of buildings in Germany. At the same time, mineral construction waste was the largest material flow at 229.3 million tons (2020).
The rates of building material recycling have increased since 2000, especially for mineral waste. Nevertheless, the majority of recycled aggregates are used in technically largely unregulated applications (e.g. road construction). This downcycling leads to a loss of valuable resources for technically and economically valuable uses.
The upMIN100 research project is investigating the question of whether and to what extent recycled mineral construction and demolition waste is suitable as an additive in earthen building materials such as earth plasters and earth blocks. The focus is placed on grain sizes < 2 mm, which are currently predominantly landfilled, as there are currently no regulations for their use in building products.
In order to enable the use of construction and demolition waste, the technical feasibility must be ensured, quality requirements for source materials (e.g. limit values for pollutants in terms of health and environmental environmental compatibility and hazardous substances) and permissible proportions of recycled aggregates must be defined.
To avoid negative impact on building occupants, the developed building materials have been tested in terms of harmful substances included in the mineral waste as well as emissions into the ambient air. Furthermore, the earthen building products, manufactured from mineral waste, should be free from pollutants to enable a return into the environment. According to the Substitute Building Materials Ordinance (EBV) this corresponds to criterion BM-0.
Two different building material developments were used to test the technical feasibility and the pollutant content of the recycled aggregate
Engineering Safety in EV's: Analysis of occupant safety using a multifunctional real-scale model car
No full textFor vehicle occupant safety, it is important to investigate the effects on people of the pollutants and temperatures emitted by electric vehicle traction batteries in the event of a fire. Fire tests on complete vehicles are the most realistic way of investigating the effects on vehicle occupants. However, these types of real fire tests are very complex and only represent one specific fire scenario with the corresponding specific boundary conditions. We would like to present an engineering method that makes it possible to investigate the effects on the occupants' ability to escape in various damage scenarios with different vehicle geometries without wasting expensive resources
Determination of uptake rates of VVOCs and carbonyls in indoor air on passive sampling system
No full textThe identity and concentration of volatile contaminants are important factors in ensuring a healthy indoor environment. Volatile organic compounds (VOCs) in indoor air can be determined by using passive samplers that are exposed to the air for a well-defined period of time. This sampling method is often used in environmental surveys, e.g. the German Environmental Survey (GerES). Conclusions about indoor air concentrations can be drawn from substance and adsorption material specific uptake rates. For the assessment of indoor air quality, highly volatile organic compounds may also be substantial, but for many of these substances realistic uptake rates and suitable analytical methods are lacking. A small chamber is used to generate gas atmospheres with constant concentrations of the analytes at 23 °C and 50 % relative humidity. For a large number of compounds, a very small flow of pure liquid VVOCs is introduced into the chamber via a syringe pump and mixed with a constant flow of clean and humidified air. A gas mixture from cylinders is also used for this purpose. Carbograph 5TD has already been proven as a suitable sorption material for active sampling for most of VVOCs. With this procedure up to 55 different VVOCs should be tested in this study. Stable concentrations of gas phase atmospheres of the first group of VVOCs (acetone, 2-butanone, methyl acrylate) were produced for exposure of passive samplers. Comparison of different adsorbent materials showed that Carbograph 5TD was the most suitable for passive sampling of these substances, with higher uptake than Carbopack X and Tenax® TA. Very strong adsorbents are not suitable for this experimental design as it adsorbs larger amounts of water. The effective uptake rates were calculated for the first three VVOCs on Carbograph 5TD tubes and an exposure time of 7 days. The same experiment will be performed for all VVOCs and ideally one material should be the best option for all of them
Using imaging ellipsometry to understand femtosecond laser materials processing of group IV materials
No full textLaser materials processing is an important tool for creating and shaping new materials. Laser machining, especially with ultrashort pulses offers the modification of surfaces, thin coatings, and bulk materials with an unprecedented precision and control. The most desired feature of pulsed laser processing in the femtosecond range is that the heat-affected zone in the irradiated material will be extremely small. To better understand the mechanisms involved during laser irradiation, it is important to analyse the outcome of light-matter interaction with spectroscopic methods. Ellipsometry, especially spectroscopic imaging ellipsometry (SIE), has become an important tool for this in recent times, as it gives access to local layer thicknesses, materials dielectric functions, and features like changes in surface roughness.
This work includes an overview over our recent studies examining near-infrared fs-laser surface processing of different group IV materials. The superficial phase change of silicon from crystalline to amorphous has been investigated in the past as the result of laser processing strongly depends on the crystal orientation. Moreover, SIE is capable of determining the
properties of buried a-Si interfaces with micrometer lateral and sub-nanoneter vertical precision. Additionally, the growth of native and laser-induced oxides can be revealed
Assessment of in service welding conditions for pressurized hydrogen pipelines via component test
No full textHydrogen is the energy carrier of tomorrow for a fossil-free future. This requires a reliable transport infrastructure with the ability to carry large amounts of hydrogen e.g. for steel industry or chemical industry. The conversion of existing natural gas (NG) grids is an essential part of the worldwide hydrogen strategies, in addition to the construction of new pipelines. In this context, the transportation of hydrogen is fundamental different from NG as hydrogen can be absorbed into the pipeline material. Given the well-known effects of hydrogen embrittlement, the compatibility of the materials for the intended pipelines must be investigated (typically low alloy steels in a wide range of strengths and thicknesses). However, pipelines require frequent maintenance, repair or the need for installation for further outlets. In some cases, it is necessary to perform welding on or onto the pipelines while they are still in service, i.e. with active gas flow under high pressure, e.g. such as the well-known “hot tapping”. This in-service welding causes challenges for hydrogen operations in terms of additional hydrogen absorption during welding and the material compatibility. The challenge can be roughly divided into the possible austenitization of the inner pipe material exposed to hydrogen, which can lead to sufficient hydrogen absorption, and the welding itself, which causes an increased temperature range. Both lead to a significant increase in hydrogen solubility and diffusivity of the respective materials compared to room temperature. In this context, knowledge about hot tapping on hydrogen pipelines is scarce due to the lack of operating experience. Fundamental experimental investigations are required to investigate the transferability from NG to hydrogen pipeline grids. For this reason, the present study introduces a specially designed mock-up / demonstrator concept for the realistic assessment of the welding processing conditions. The mock-up was designed to enable in-situ temperature measurement during welding as well as ex-post extraction of samples for the quantification of the absorbed hydrogen concentration. For safety measures, the necessary pressurized hydrogen volume was limited by the insertion of a solid cylinder ensuring a 1 cm hydrogen gas layer. Welding experiments on the pressurized mock-ups with the diameters DN60 and DN200 have shown that the austenitization temperature can be reached on the inner surface of the pipeline, especially on thinner walled pipelines, using current welding practices. This corresponds to an increased hydrogen uptake in the welded area of several ppm
Inspection with multisensor laser thermography
No full textThe automated testing of complex, highly stressed components requires advanced methods capable of detecting various forms of defects with precision and reliability. In this work we present our approach by combining robotic automation with laser thermography, as a versatile and efficient solution for inspecting intricate geometries under demanding industrial conditions.
Central to this approach is the integration of a fiber-coupled laser as a flexible heat source, a high-performance thermal imaging system, an industrial robot, additional visible camera systems, different IR emitters and intelligent signal processing algorithms. This allows, after an initial fully-automated mapping of the part geometry and position that the object under test is thermographically tested for surface or bulk defects. Interferences caused by unideal surface conditions can be corrected for using simultaneously obtained optical images. Finally, all test results can be mapped onto a digital representation of the object leading to a fully digital and machine-readable documentation that can be used for quality assurance.
This combination therefore enables accurate defect detection and characterization, overcoming traditional limitations associated with material variability and surface inhomogeneities. The system's adaptability allows for tailored solutions that address real-world challenges, ensuring reliable and repeatable results across diverse applications.
The proposed methodology emphasizes the synergy between robotics, active thermography, and advanced data analysis to achieve high levels of precision and automation. This work highlights the potential of these technologies to optimize quality assurance processes and contribute to innovation in various industrial sectors
Modern welding processes for optimizing repair welding on high-strength offshore steels
No full textThe successful energy transition in Germany will require offshore wind turbines with outputs >10 MW in the future, for which high-strength steels with a yield strength of up to 500 MPa and wall thicknesses up to 150 mm are increasingly being used. The repair of weld seams when detecting defects during NDT requires localized gouging and rewelding. This involves high demands on welding manufacturing, especially for highstrength steels. Due to a lack of investigations, there are no repair concepts and information in standards and guidelines, particularly for high-strength thick plate joints made of high-strength offshore steels. However, these are urgently needed to enable processors, especially SMEs, to carry out safe and economical repairs. Therefore, BAM startedthe FOSTA project P1629 (IGF 01IF22746N) to investigate the stress-optimized repair(local gouging and welding) of high-strength thick plate joints made of offshore grades in the yield strength range off 355 to 460 MPa and similar weld metal with controlled high-performance GMAW processes and optimized narrower gouging grooves. The experimental analyses consider the complex interaction of material, process, and designrelated influences on the formation of weld-related stresses and the special microstructure of high-strength fine-grain structural steels. Welding-related material Degradation and crack-critical residual tensile stresses need to be avoided to ensure high component safety and performance. With component-related welding experiments on special testing equipment, adapted process and heat control concepts along with variable groove configurations will be developed and recommendations for guidelines elaborated. This is the prerequisite for fully utilizing the strength potential of high-strength steels and making a valuable contribution to the energy transition in Germany, especially for steelprocessing SMEs
Cryogenic LH2 Storage Vessels in a Fire
No full textTo investigate the hazards emanating from cryogenic LH2 storage Vessels in a fire, experiments have been performed at the Test Site Technical Safety of the Bundesanstalt für Materialforschung und –prüfung (BAM), Germany. Three double-walled vacuum insulated vessels of 1 m3 volume, filled to approximately 35-40 Vol.% with LH2 were put in a fire. The cylindrical Vessels differed in orientation (horizontal or vertical) and the insulationmaterial used (perlite or multi-layer insulation (MLI)). The fire load was provided by a propane fed burner-system positioned under the storage vessel and designed to give a homogeneous fire load. During the tests the conditions in the vessel (temperatures and pressure) as well as external effects (heat radiation, blast waves, flame ball development and fragmentation) were measured. Two of these vessels, a horizontal and a vertical vessel both insulated with perlite withstood the fire loading for 1 hour 20 minutes and 4 hours respectively without catastrophic failure, but partly showing leakages. The horizontal vessel insulated with MLI failed by bursting after 1 hour and 6 minutes resulting in a fireball, fragments, and blast wave. The test results as well as the detailed examination of the non-destroyed vessels rose some interesting questions which type of insulation might be better to protect a vessel not only during its normal operation but also under fire loading against a heat flux from the surroundings, as well as to the suitability of cryogenic (safety) equipment under fire loading