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Ali, H., Rusz, J., Bürgler, D. E., Adam, R., Schneider, C. M., Tai, C.-W. & Thersleff, T. (2024). Noise-dependent bias in quantitative STEM-EMCD experiments revealed by bootstrapping. Ultramicroscopy, 257, Article ID 113891.
Open this publication in new window or tab >>Noise-dependent bias in quantitative STEM-EMCD experiments revealed by bootstrapping
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2024 (English)In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 257, article id 113891Article in journal (Refereed) Published
Abstract [en]

Electron magnetic circular dichroism (EMCD) is a powerful technique for estimating element-specific magnetic moments of materials on nanoscale with the potential to reach atomic resolution in transmission electron microscopes. However, the fundamentally weak EMCD signal strength complicates quantification of magnetic moments, as this requires very high precision, especially in the denominator of the sum rules. Here, we employ a statistical resampling technique known as bootstrapping to an experimental EMCD dataset to produce an empirical estimate of the noise-dependent error distribution resulting from application of EMCD sum rules to bcc iron in a 3-beam orientation. We observe clear experimental evidence that noisy EMCD signals preferentially bias the estimation of magnetic moments, further supporting this with error distributions produced by Monte-Carlo simulations. Finally, we propose guidelines for the recognition and minimization of this bias in the estimation of magnetic moments.

Keywords
Electron magnetic circular dichroism, Electron energy loss spectroscopy, Scanning, Transmission electron microscopy, Bootstrapping, Noise dependent bias, Error analysis
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:su:diva-225757 (URN)10.1016/j.ultramic.2023.113891 (DOI)001132754500001 ()38043363 (PubMedID)2-s2.0-85178597506 (Scopus ID)
Available from: 2024-01-23 Created: 2024-01-23 Last updated: 2024-01-30Bibliographically approved
Mikheenkova, A., Mukherjee, S., Hirsbrunner, M., Törnblom, P., Tai, C.-W., Segre, C. U., . . . Hahlin, M. (2024). The role of oxygen in automotive grade lithium-ion battery cathodes: an atomistic survey of ageing. Journal of Materials Chemistry A, 12(4), 2465-2478
Open this publication in new window or tab >>The role of oxygen in automotive grade lithium-ion battery cathodes: an atomistic survey of ageing
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2024 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, E-ISSN 2050-7496, Vol. 12, no 4, p. 2465-2478Article in journal (Refereed) Published
Abstract [en]

The rising demand for high-performance lithium-ion batteries, pivotal to electric transportation, hinges on key materials like the Ni-rich layered oxide LiNixCoyAlzO2 (NCA) used in cathodes. The present study investigates the redox mechanisms, with particular focus on the role of oxygen in commercial NCA electrodes, both fresh and aged under various conditions (aged cells have performed >900 cycles until a cathode capacity retention of ∼80%). Our findings reveal that oxygen participates in charge compensation during NCA delithiation, both through changes in transition metal (TM)–O bond hybridization and formation of partially reversible O2, the latter occurs already below 3.8 V vs. Li/Li+. Aged NCA material undergoes more significant changes in TM–O bond hybridization when cycling above 50% SoC, while reversible O2 formation is maintained. Nickel is found to be redox active throughout the entire delithiation and shows a more classical oxidation state change during cycling with smaller changes in the Ni–O hybridization. By contrast, Co redox activity relies on a stronger change in Co–O hybridization, with only smaller Co oxidation state changes. The Ni–O bond displays an almost twice as large change in its bond length on cycling as the Co–O bond. The Ni–O6 octahedra are similar in size to the Co–O6 octahedra in the delithiated state, but are larger in the lithiated state, a size difference that increases with battery ageing. These contrasting redox activities are reflected directly in structural changes. The NCA material exhibits the formation of nanopores upon ageing, and a possible connection to oxygen redox activity is discussed. The difference in interaction of Ni and Co with oxygen provides a key understanding of the mechanism and the electrochemical instability of Ni-rich layered transition metal oxide electrodes. Our research specifically highlights the significance of the role of oxygen in the electrochemical performance of electric-vehicle-grade NCA electrodes, offering important insights for the creation of next-generation long-lived lithium-ion batteries.

National Category
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-226137 (URN)10.1039/d3ta05516g (DOI)001135752700001 ()38269086 (PubMedID)2-s2.0-85182225074 (Scopus ID)
Available from: 2024-02-01 Created: 2024-02-01 Last updated: 2024-02-01Bibliographically approved
Rafi, A. A., Alimohammadzadeh, R., Avella, A., Mõistlik, T., Jűrisoo, M., Kaaver, A., . . . Cordova, A. (2023). A facile route for concurrent fabrication and surface selective functionalization of cellulose nanofibers by lactic acid mediated catalysis. Scientific Reports, 13, Article ID 14730.
Open this publication in new window or tab >>A facile route for concurrent fabrication and surface selective functionalization of cellulose nanofibers by lactic acid mediated catalysis
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2023 (English)In: Scientific Reports, E-ISSN 2045-2322, Vol. 13, article id 14730Article in journal (Refereed) Published
Abstract [en]

Celulose nanofibers are lightweight, recycable, biodegradable, and renewable. Hence, there is a great interest of using them instead of fossil-based components in new materials and biocomposites. In this study, we disclose an environmentally benign (green) one-step reaction approach to fabricate lactic acid ester functionalized cellulose nanofibrils from wood-derived pulp fibers in high yields. This was accomplished by converting wood-derived pulp fibers to nanofibrillated “cellulose lactate” under mild conditions using lactic acid as both the reaction media and catalyst. Thus, in parallel to the cellulose nanofibril production, concurrent lactic acid-catalyzed esterification of lactic acid to the cellulose nanofibers surface occured. The direct lactic acid esterification, which is a surface selective functionalization and reversible (de-attaching the ester groups by cleavage of the ester bonds), of the cellulose nanofibrils was confirmed by low numbers of degree of substitution, and FT-IR analyses. Thus, autocatalytic esterification and cellulose hydrolysis occurred without the need of metal based or a harsh mineral acid catalysts, which has disadvantages such as acid corrosiveness and high recovery cost of acid. Moreover, adding a mineral acid as a co-catalyst significantly decreased the yield of the nanocellulose. The lactic acid media is successfully recycled in multiple reaction cycles producing the corresponding nanocellulose fibers in high yields. The disclosed green cellulose nanofibril production route is industrial relevant and gives direct access to nanocellulose for use in variety of applications such as sustainable filaments, composites, packaging and strengthening of recycled fibers.

National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:su:diva-226642 (URN)10.1038/s41598-023-41989-3 (DOI)001142021200013 ()37679445 (PubMedID)2-s2.0-85170181889 (Scopus ID)
Available from: 2024-02-15 Created: 2024-02-15 Last updated: 2024-02-15Bibliographically approved
Li, S., Chai, Z., Wang, Z., Tai, C.-W., Zhu, J., Edström, K. & Ma, Y. (2023). A Multiscale, Dynamic Elucidation of Li Solubility in the Alloy and Metallic Plating Process. Advanced Materials, 35(47), Article ID 2306826.
Open this publication in new window or tab >>A Multiscale, Dynamic Elucidation of Li Solubility in the Alloy and Metallic Plating Process
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2023 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 35, no 47, article id 2306826Article in journal (Refereed) Published
Abstract [en]

Li-containing alloys and metallic deposits offer substantial Li+ storage capacities as alternative anodes to commercial graphite. However, the thermodynamically in sequence, yet kinetically competitive mechanism between Li solubility in the solid solution and intermediate alloy-induced Li deposition remains debated, particularly across the multiple scales. The elucidation of the mechanism is rather challenging due to the dynamic alloy evolution upon the non-equilibrium, transient lithiation processes under coupled physical fields. Here, influential factors governing Li solubility in the Li-Zn alloy are comprehensively investigated as a demonstrative model, spanning from the bulk electrolyte solution to the ion diffusion within the electrode. Through real-time phase tracking and spatial distribution analysis of intermediate alloy/Li metallic species at varied temperatures, current densities and particle sizes, the driving force of Li solubility and metallic plating along the Li migration pathway are probed in-depth. This study investigates the correlation between kinetics (pronounced concentration polarization, miscibility gap in lattice grains) and rate-limiting interfacial charge transfer thermodynamics in dedicating the Li diffusion into the solid solution. Additionally, the lithiophilic alloy sites with the balanced diffusion barrier and Li adsorption energy are explored to favor the homogeneous metal plating, which provides new insights for the rational innovation of high-capacity alloy/metallic anodes.

Keywords
decoupled physical fields, dynamic phasic change, lithiophilic alloys, multiscale Li+ migration pathways, operando characterization
National Category
Materials Chemistry Physical Chemistry
Identifiers
urn:nbn:se:su:diva-223749 (URN)10.1002/adma.202306826 (DOI)001084858600001 ()37769145 (PubMedID)2-s2.0-85174214723 (Scopus ID)
Available from: 2023-11-17 Created: 2023-11-17 Last updated: 2024-01-11Bibliographically approved
Mikheenkova, A., Smith, A. J., Frenander, K. B., Tesfamhret, Y., Chowdhury, N. R., Tai, C.-W., . . . Lacey, M. J. (2023). Ageing of High Energy Density Automotive Li-Ion Batteries: The Effect of Temperature and State-of-Charge. Journal of the Electrochemical Society, 170(8), Article ID 080503.
Open this publication in new window or tab >>Ageing of High Energy Density Automotive Li-Ion Batteries: The Effect of Temperature and State-of-Charge
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2023 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 170, no 8, article id 080503Article in journal (Refereed) Published
Abstract [en]

Lithium ion batteries (LIB) have become a cornerstone of the shift to electric transportation. In an attempt to decrease the production load and prolong battery life, understanding different degradation mechanisms in state-of-the-art LIBs is essential. Here, we analyze how operational temperature and state-of-charge (SoC) range in cycling influence the ageing of automotive grade 21700 batteries, extracted from a Tesla 3 long Range 2018 battery pack with positive electrode containing LiNi(x)CoyAl(z)O(2) (NCA) and negative electrode containing SiOx-C. In the given study we use a combination of electrochemical and material analysis to understand degradation sources in the cell. Herein we show that loss of lithium inventory is the main degradation mode in the cells, with loss of material on the negative electrode as there is a significant contributor when cycled in the low SoC range. Degradation of NCA dominates at elevated temperatures with combination of cycling to high SoC (beyond 50%). (c) 2023 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BYNC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: permissions@ioppublishing.org.

National Category
Materials Engineering Materials Chemistry
Identifiers
urn:nbn:se:su:diva-221347 (URN)10.1149/1945-7111/aceb8f (DOI)001044526800001 ()2-s2.0-85167873770 (Scopus ID)
Available from: 2023-09-25 Created: 2023-09-25 Last updated: 2023-09-25Bibliographically approved
Deiana, L., Rafi, A. A., Tai, C.-W., Bäckvall, J.-E. & Cordova, A. (2023). Artificial Arthropod Exoskeletons/Fungi Cell Walls Integrating Metal and Biocatalysts for Heterogeneous Synergistic Catalysis of Asymmetric Cascade Transformations. ChemCatChem, 15(15), Article ID e202300250.
Open this publication in new window or tab >>Artificial Arthropod Exoskeletons/Fungi Cell Walls Integrating Metal and Biocatalysts for Heterogeneous Synergistic Catalysis of Asymmetric Cascade Transformations
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2023 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 15, no 15, article id e202300250Article in journal (Refereed) Published
Abstract [en]

A novel and sustainable tandem-catalysis system for asymmetric synthesis is disclosed, which is fabricated by bio-inspired self-assembly of artificial arthropod exoskeletons (AAEs) or artificial fungi cell walls (AFCWs) containing two different types of catalysts (enzyme and metal nanoparticles). The heterogeneous integrated enzyme/metal nanoparticle AAE/AFCW systems, which contain chitosan as the main structural component, co-catalyze dynamic kinetic resolution of primary amines via a tandem racemization/enantioselective amidation reaction process to give the corresponding amides in high yields and excellent ee. The heterogeneous AAE/AFCW systems display successful heterogeneous synergistic catalysis at the surfaces since they can catalyze multiple reaction cycles without metal leaching. The use of natural-based and biocompatible structural components makes the AAE/AFCW systems fully biodegradable and renewable, thus fulfilling important green chemistry requirements. 

Keywords
asymmetric tandem catalysis, chiral amines, chitosan, dynamic kinetic resolution, heterogeneous hybrid catalyst
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:su:diva-221309 (URN)10.1002/cctc.202300250 (DOI)001022816700001 ()2-s2.0-85164018579 (Scopus ID)
Available from: 2023-09-19 Created: 2023-09-19 Last updated: 2023-09-21Bibliographically approved
Deiana, L., Badali, E., Rafi, A. A., Tai, C.-W., Bäckvall, J.-E. & Cordova, A. (2023). Cellulose-Supported Heterogeneous Gold-Catalyzed Cycloisomerization Reactions of Alkynoic Acids and Allenynamides. ACS Catalysis, 13(15), 10418-10424
Open this publication in new window or tab >>Cellulose-Supported Heterogeneous Gold-Catalyzed Cycloisomerization Reactions of Alkynoic Acids and Allenynamides
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2023 (English)In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 13, no 15, p. 10418-10424Article in journal (Refereed) Published
Abstract [en]

Herein, we describe efficient nanogold-catalyzed cycloisomerization reactions of alkynoic acids and allenynamides to enol lactones and dihydropyrroles, respectively (the latter via an Alder-ene reaction). The gold nanoparticles were immobilized on thiol-functionalized microcrystalline cellulose and characterized by electron microscopy (HAADF-STEM) and by XPS. The thiol-stabilized gold nanoparticles (Au-0) were obtained in the size range 1.5-6 nm at the cellulose surface. The robust and sustainable cellulose-supported gold nanocatalyst can be recycled for multiple cycles without losing activity.

Keywords
cellulose-supported nanogold catalysis, C-C bondformation, heterogeneous catalysis, cycloisomerization, heterocycles, Alder-ene reaction
National Category
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-223193 (URN)10.1021/acscatal.3c02722 (DOI)001066876500001 ()37560186 (PubMedID)2-s2.0-85167895594 (Scopus ID)
Available from: 2023-10-24 Created: 2023-10-24 Last updated: 2023-10-24Bibliographically approved
Valvo, M., Chien, Y.-C., Liivat, A. & Tai, C.-W. (2023). Detecting voltage shifts and charge storage anomalies by iron nanoparticles in three-electrode cells based on converted iron oxide and lithium iron phosphate. Electrochimica Acta, 440, Article ID 141747.
Open this publication in new window or tab >>Detecting voltage shifts and charge storage anomalies by iron nanoparticles in three-electrode cells based on converted iron oxide and lithium iron phosphate
2023 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 440, article id 141747Article in journal (Refereed) Published
Abstract [en]

Noticeable voltage shifts have been observed in the charge/discharge profiles of a three-electrode cell with a lithium metal reference electrode and having a deeply lithiated iron oxide (Fe/Li2O) negative electrode galvanostatically cycled in a limited potential range against a positive LiFePO4 counterpart. The origin of such shifts has been attributed to charge storage anomalies in the Fe/Li2O nanocomposite due to characteristic reduced Fe nanoparticle sizes. These shifts also affected the extreme points of the voltage profiles of the positive electrode, which was also independently monitored. A combined evaluation of voltage profile slippages with possible changes in internal resistance and/or Li+ inventory loss, including an aimed analysis of current interruptions at the end of each lithiation/de-lithiation half-cycle to monitor the internal resistance and diffusion resistance coefficient of the Fe/Li2O electrode, has enabled a clarification of its altered charge storage. An asymmetric behaviour of the Fe/Li2O electrode during Li+ uptake/release has been revealed, highlighting a progressive, diffusion-controlled-type voltage drift at low potentials vs. Li+/Li, and an unusual tendency to slight oxidation with capacitive variations during the reverse electrochemical processes at higher voltages, instead.

Keywords
Conversion reactions, Metal nanoparticles, Capacitance, Size effects, Li-ion batteries
National Category
Chemical Sciences
Identifiers
urn:nbn:se:su:diva-214857 (URN)10.1016/j.electacta.2022.141747 (DOI)000916016500001 ()2-s2.0-85144604440 (Scopus ID)
Available from: 2023-03-06 Created: 2023-03-06 Last updated: 2023-03-06Bibliographically approved
Ramesh Naidu, V., Rafi, A. A., Tai, C.-W., Bäckvall, J. E. & Córdova, A. (2023). Regio- and Stereoselective Carbon-Boron Bond Formation via Heterogeneous Palladium-Catalyzed Hydroboration of Enallenes. Chemistry - A European Journal, 29(24), Article ID e202203950.
Open this publication in new window or tab >>Regio- and Stereoselective Carbon-Boron Bond Formation via Heterogeneous Palladium-Catalyzed Hydroboration of Enallenes
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2023 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 29, no 24, article id e202203950Article in journal (Refereed) Published
Abstract [en]

A highly efficient regio- and stereoselective heterogeneous palladium-catalyzed hydroboration reaction of enallenes was developed. Nanopalladium immobilized on microcrystalline cellulose (MCC) was successfully employed as an efficient catalyst for the enallene hydroboration reaction. The nanopalladium particles were shown by HAADF-STEM to have an average size of 2.4 nm. The cellulose-supported palladium catalyst exhibits high stability and provides vinyl boron products in good to high isolated yields (up to 90 %). The nanopalladium catalyst can be efficiently recycled and it was demonstrated that the catalyst can be used in 7 runs with a maintained high yield (>80 %). The vinylboron compounds prepared from enallenes are important synthetic intermediates that can be used in various organic synthetic transformations. 

Keywords
cellulose, enallenes, heterogeneous catalysis, palladium, regio- and stereoselective hydroboration
National Category
Organic Chemistry
Identifiers
urn:nbn:se:su:diva-216462 (URN)10.1002/chem.202203950 (DOI)000953617500001 ()36719323 (PubMedID)2-s2.0-85150410152 (Scopus ID)
Available from: 2023-05-02 Created: 2023-05-02 Last updated: 2023-09-22Bibliographically approved
Ali, H., Sathyanath, S. K., Tai, C.-W., Rusz, J., Uusimaki, T., Hjorvarsson, B., . . . Leifer, K. (2023). Single scan STEM-EMCD in 3-beam orientation using a quadruple aperture. Ultramicroscopy, 251, Article ID 113760.
Open this publication in new window or tab >>Single scan STEM-EMCD in 3-beam orientation using a quadruple aperture
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2023 (English)In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 251, article id 113760Article in journal (Refereed) Published
Abstract [en]

The need to acquire multiple angle-resolved electron energy loss spectra (EELS) is one of the several critical challenges associated with electron magnetic circular dichroism (EMCD) experiments. If the experiments are performed by scanning a nanometer to atomic-sized electron probe on a specific region of a sample, the precision of the local magnetic information extracted from such data highly depends on the accuracy of the spatial registration between multiple scans. For an EMCD experiment in a 3-beam orientation, this means that the same specimen area must be scanned four times while keeping all the experimental conditions same. This is a non-trivial task as there is a high chance of morphological and chemical modification as well as non-systematic local orientation variations of the crystal between the different scans due to beam damage, contamination and spatial drift. In this work, we employ a custom-made quadruple aperture to acquire the four EELS spectra needed for the EMCD analysis in a single electron beam scan, thus removing the above-mentioned complexities. We demonstrate a quantitative EMCD result for a beam convergence angle corresponding to sub-nm probe size and compare the EMCD results for different detector geometries.

National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:su:diva-221404 (URN)10.1016/j.ultramic.2023.113760 (DOI)001016715300001 ()37285614 (PubMedID)2-s2.0-85161307125 (Scopus ID)
Available from: 2023-09-20 Created: 2023-09-20 Last updated: 2024-01-30Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-7286-1211

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