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JLUpub bietet Mitgliedern und Angehörigen der Universität die Möglichkeit neben wissenschaftlichen Dokumenten auch Forschungsdaten elektronisch zu veröffentlichen und dauerhaft zugänglich zu machen. Alle Veröffentlichungen erhalten einen Digital Object Identifier (DOI) und werden über nationale und internationale Bibliothekskataloge sowie Suchmaschinen nachgewiesen und auffindbar.
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Item type: Item , Impedance spectroscopy using microscopic reference electrodes to analyze different rate-determining steps in aqueous dye-sensitized solar cells using nitroxide radicals as redox mediators(2024) Holzhacker, Daniel; Ringleb, Andreas; Schlettwein, DerckFor new components in dye-sensitized solar cells (DSSCs), identification and quantification of rate-limiting steps is needed to evaluate their applicability. This is particularly important if fundamental changes are studied. In this work, the use of a micro-reference electrode in DSSCs is proposed to increase the significance of electrochemical impedance spectroscopy. The recombination of charge carriers at the photoanode and the regeneration of redox mediators at the counter electrode, which typically occur on similar timescales, could be studied separately but simultaneously in cells under operating conditions. This is particularly useful in the study of water-based DSSCs. Here, cells with 2,2,6,6-Tetramethylpiperidinoxyl (TEMPO) or 4-Hydroxy-TEMPO (OH-TEMPO) as redox mediators using additives like 1-Methylbenzimidazole (MBI) are discussed. It was revealed that the charge transfer resistance (RCE) for the reduction of the oxidized redox mediator at the counter electrode (CE) limits the fill factor (FF) of such DSSCs. TEMPO/MBI electrolytes yielded low RCE and high FF, whereas OH-TEMPO in otherwise identical cells resulted in large RCE, low FF, and low conversion efficiencies. This indicates that the interface between the CE and the electrolyte significantly influences the DSSC performance of these cells and strongly depends on the electrolyte composition. Important optimization strategies could be discussed based on the present results.Item type: Item , Interphase Growth Kinetics and the Partial Electronic Conductivity of Constituents in Sulfide Solid-State Batteries(2025-06) Alt, Christoph DanielLarge-scale electrification of transportation and advancements in energy storage are key to achieving net-zero emissions. Solid-state batteries present a promising energy storage solution, expected to enable the use of high-capacity electrode materials such as lithium metal and lithium alloys, while also improving safety. However, effectively integrating high-capacity electrode materials remains a key challenge in unlocking the potential of solid-state batteries. The high reactivity of lithium metal poses both safety and operational challenges, leading to dendrite formation and loss of active redox species (i.e., long-term capacity fading). Since most inorganic solid electrolytes undergo reduction upon contact with alkali metal, the corresponding interphase formation and the resulting long-term increase in cell resistance are often underestimated. However, interphase kinetics and the consequent impact on cell performance strongly depend on the composition and properties of the reaction products. Revealing the interphase composition, growth kinetics, and the influence and role of its individual constitu-ents is crucial for developing protective strategies and enhancing material compatibility. Within this doctoral thesis, the intrinsic transport properties and growth kinetics of the interphase and its constituents for lithiated Li6PS5Cl are investigated, emphasizing their impact on long-term cell operation. Following the quantification of the interphase's partial conductivities through bulk-material synthesis, which revealed a significant resistance contribution over the battery's lifespan, conventional physiochemical concepts were revisited. The Wagner diffusion model, predicting diffusion-controlled interphase growth based on experimental data, was analyzed for solid|solid interfaces alongside the Hebb-Wagner method for accurately quantifying low electronic conductivities in lithium-ion conductors. The former addressed the influence of different interface morphologies on evaluating interphase rate constants by impedance measurements, while the latter revealed the partial electronic conductivity of lithium halides (i.e., LiCl, LiBr, and LiI) present in various interphases. Alloy electrodes, owing to their higher electrode potentials relative to lithium metal, are expected to cause reduced degradation of sulfide solid electrolytes. In this context, In/(InLi)x electrodes – prominent for exhibiting a stable potential of 0.62 V vs. Li+/Li – were first investigated to assess how preparation influences electrode microstructure and performance. Controlling microstructure is critical to avoid current constriction and ensure consistent operation. Studies on thin indium films deposited on current collectors offered insights into interphase growth kinetics at alloying interlayers – an essential challenge for reservoir-free cells – and highlighted the gradual degradation of Li6PS5Cl at the electrode potential of In/(InLi)x. Overall, this doctoral thesis advances the fundamental understanding of intrinsic degradation processes at the electrode|electrolyte interface. In particular, this work provides a new perspective on how multiphase interphases form and evolve over time, depending on their partial ionic and electronic transport properties. It delivers essential insights on previously inaccessible kinetic parameters that now enable more accurate computational simulations, improve the prediction by analytical models, and guide the rational design of more stable materials and interfaces to minimize capacity losses in (reservoir-free) solid-state batteries.Item type: Item , Does the Eco-Score lead to a halo effect? Influence of a sustainability label on product perceptions and purchase intention(2024) Büttner, Verena; Gassler, Birgit; Teuber, RamonaThe Eco-Score is an approach to make the environmental impact of a food product visible using color-coded labeling. Previous research has shown the potential of organic and ethical labels to influence consumers’ perceptions of other product features – what is called the halo effect. Using an online questionnaire with a between-subject design and a representative sample for Germany (N = 1010), we examined whether the Eco-Score might also induce halo effects. Therefore, we evaluated how consumers assess the perceived environmental friendliness, expected tastiness, and perceived healthiness of packaged foods with or without an Eco-Score. We consider three different products (spaghetti, yoghurt, and crisps) in three treatment groups (Eco-Scores A, C, and E) and one control group (no label). For our statistical analyses, we employed repeated-measures ANOVAs and regression-based mediation analyses. Our results show that products are perceived as more (Eco-Score A) or less (Eco-Score E) environmentally friendly when labelled with the Eco-Score and this perception mediates the purchase intention positively or negatively, respectively. Furthermore, our results suggest that the Eco-Score can bias consumer perceptions of other food product characteristics. In particular, the Eco-Score E negatively influences expected tastiness and perceived healthiness, which lowers purchase intention. Regression-based moderation analyses show further that participants with high environmental or health concern are in part more susceptible to positive halo effects. However, overall, the moderator effects are small. The paper extends the literature on halo effects related to food labeling and hence provides important insights on perceptions of food products labelled with a color-coded scoring system. Theoretical and practical implications as well as avenues for future research are discussed.Item type: Item , Individual participant data analysis comparing acute stroke patients with anterior versus posterior circulation dissections(2024) Zhang, Yanan; Zhang, Yang; Froehlich, Kilian; Mrochen, Anne; Muehlen, Iris; Lang, Stefan; Lehmann, Sophie; Gerner, Stefan T.; Huttner, Hagen B.; Schwab, Stefan; He, Li; Bobinger, TobiasBackground: Cervical artery dissection (CAD) is a relevant etiology of transient ischemic attacks and strokes. Several trials explored the significance of specific antithrombotic treatments, i.e. oral anticoagulation (OAC) versus antiplatelet treatment (APT), on recurrent ischemic complications and clinical outcomes. As overall incidence rates of complications were low there is still controversy which antithrombotic treatment should be used. However, up to now there has been no systematic investigation among CAD-patients with ischemic stroke specifically comparing clinical course and outcome of patients with anterior versus posterior CAD. Methods: We performed an individual participant data analysis of patients with CAD and ischemic stroke. Over a five-year period we pooled data from three sites (i.e. West China Hospital, Chengdu, China as well as Erlangen and Giessen University Hospitals, Germany) and enrolled patients with CAD-associated ischemic stroke. Patient demographics, clinical and in-hospital measures as well as radiological data were retrieved from institutional databases. Clinical follow-up was over 6 months and included data on recurrent ischemic strokes and hemorrhages as well as clinical functional outcome assessed by the modified Rankin Scale dichotomized into favourable (mRS=0–2) and unfavourable. Results: A total of 203 patients with CAD were included of which n=112 had anterior and n=91 had posterior CAD. Patients with posterior CAD were younger (46.0 vs. 41.0 y; p<0.001) than patients with anterior CAD and showed less often arterial hypertension. (42.0 % vs. 28.6 %; p<0.048). Antithrombotic treatment with APT and OAC was similarily distributed among patients with anterior and posterior CAD and not significantly differently related to ischemic or hemorrhagic complications during follow-up (all p=n.s.). Main difference between Chinese and German patients were mode of antithrombotic treatment consisting predominantly of APT in China compared to OAC in Germany. Functional outcome overall was good, yet worse in patients with anterior CAD compared to posterior CAD (80.2 % favorable in anterior CAD vs. 92.2 % in posterior CAD (p=0.014). Conclusion: This study provides evidence that anterior and posterior CAD show baseline imbalances regarding age and comorbidity which may affect clinical outcome. There are no signals of superiority or harm of any specific mode of antithrombotic treatment nor relevant discrepancies in clinical outcome among Chinese and German CAD-associated stroke patients.Item type: Item , Fertilization efficiency of thirty marketed and experimental recycled phosphorus fertilizers(2024) Hernandez-Mora, A.; Duboc, O.; Lombi, E.; Bünemann, E.K.; Ylivainio, K.; Symanczik, S.; Delgado, A.; Abu Zahra, N.; Nikama, J.; Zuin, L.; Doolette, C.L.; Eigner, H.; Santner, J.Recycling phosphorus (P) from waste streams like sewage sludge, animal manures or food industry by-products is required to sustain soil fertility without depleting non-renewable P resources. Several technologies are available for P recovery, leading to fertilizers differing in P solubility and bioavailability. In this study, thirty fertilizers obtained through different technologies were tested to assess if their fertilization efficiency was equivalent to mineral soluble fertilizer applied as triple superphosphate (TSP). The main selection criteria were (1) ensuring a wide chemical diversity, and (2) choosing products already on the market or at a late stage of development, to encompass a representative selection of current and future recycled fertilizers. The products were classified according to their organic carbon content and neutral ammonium citrate (NAC), and the main P species of each fertilizer was determined through K-edge and L2,3-edge X-ray absorption near edge structure spectroscopy (XANES). Three pot experiments with wheat, barley and ryegrass were conducted in three growing substrates with contrasting properties, all within a pH range of 5.8–6.9. Fertilizers containing ammonium magnesium phosphate, monoammonium phosphate, monocalcium phosphate, and dicalcium phosphate type species as dominant P species showed a similar fertilization efficiency to TSP, while fertilizers with hydroxyapatite, tricalcium phosphate, phytic acid or iron phosphates as their main P species had lower fertilization efficiencies. We conclude that while the trend towards high-efficiency, refined inorganic recycled P fertilizers is positive, lower-performing, mostly unrefined fertilizers must be assessed in light of their long-term P supply potential and additional benefits to soil health owing to their content of organic matter and other nutrients.