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147 results on '"Mullaliu, Angelo"'

8. Mechanism Insight into Direct Amidation Catalyzed by Zr Salts: Evidence of Zr Oxo Clusters as Active Species

Author

Zhang, Yujie, Puiggalí-Jou, Jordi, Mullaliu, Angelo, Solé-Daura, Albert, Carbó, Jorge J., Parac-Vogt, Tatjana N., and de Azambuja, Francisco

Abstract

The capricious reactivity and speciation of earth-abundant metals (EAM) hinder the mechanistic understanding essential to boost their efficiency and versatility in catalysis. Moreover, metal’s solution chemistry and reactivity are conventionally controlled using organic ligands, while their fundamental chemistry in operando conditions is often overlooked. However, in this study, we showcase how a better understanding of in operando conditions may result in improved catalytic reactions. By assessing the composition and structure of active species for Zr-catalyzed direct amide bond formations under operating conditions, we discovered zirconium oxo clusters form quickly and are likely active species in the reactions. Formation of these clusters dismisses the use of additional organic ligands, inert atmosphere, anhydrous solvents, or even water scavenging to provide amides in good to excellent yields. More specifically, dodeca- and hexazirconium oxo clusters (Zr12and Zr6, respectively) rapidly form from commercial, readily available Zr salts under reaction conditions known to afford amides directly from nonactivated carboxylic acid and amine substrates. Extended X-ray absorption fine structure (EXAFS) experiments confirm the presence of oxo clusters in solution throughout the reaction, while their key role in the mechanism is supported by an in-depth computational study employing density functional theory (DFT) and molecular dynamics (MD) methods. These results underline the value of (earth-abundant) metals’ intrinsic solution chemistry to transformative mechanistic understanding and to enhance the sustainability of organic transformations.

Published
2024
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9. Mapping Heterogeneity of Pristine and Aged Li- and Na-Mnhcf Cathode by Synchrotron-Based Energy-Dependent Full Field Transmission X-ray Microscopy

Author

Università di Bologna, Centro Nazionale per la mobilità sostenibile, Helmholtz Association, Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Ciencia e Innovación (España), Agencia Estatal de Investigación (España), European Commission, Maisuradze, Mariam [0000-0002-1498-1706], Mullaliu, Angelo [0000-0003-2800-2836], Sorrentino, Andrea [0000-0002-3235-8950], Tonti, Dino [0000-0003-0240-1011], Passerini, Stefano [0000-0002-6606-5304], Giorgetti, Marco [0000-0001-7967-8364], Maisuradze, Mariam, Li, Min, Mullaliu, Angelo, Sorrentino, Andrea, Tonti, Dino, Passerini, Stefano, Giorgetti, Marco, Università di Bologna, Centro Nazionale per la mobilità sostenibile, Helmholtz Association, Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Ciencia e Innovación (España), Agencia Estatal de Investigación (España), European Commission, Maisuradze, Mariam [0000-0002-1498-1706], Mullaliu, Angelo [0000-0003-2800-2836], Sorrentino, Andrea [0000-0002-3235-8950], Tonti, Dino [0000-0003-0240-1011], Passerini, Stefano [0000-0002-6606-5304], Giorgetti, Marco [0000-0001-7967-8364], Maisuradze, Mariam, Li, Min, Mullaliu, Angelo, Sorrentino, Andrea, Tonti, Dino, Passerini, Stefano, and Giorgetti, Marco

Abstract

Manganese hexacyanoferrate is a promising cathode material for lithium and sodium ion batteries, however, it suffers of capacity fading during the cycling process. To access the structural and functional characteristics at the nanometer scale, fresh and cycled electrodes are extracted and investigated by transmission soft X-ray microscopy, which allows chemical characterization with spatial resolution from position-dependent x-ray spectra at the Mn L-, Fe L- and N K-edges. Furthermore, soft X-rays prove to show superior sensitivity toward Fe, compare to hard X-rays. Inhomogeneities within the samples are identified, increasing in the aged electrodes, more dramatically in the Li-ion system, which explains the poorer cycle life as Li-ion cathode material. Local spectra, revealing different oxidation states over the sample with strong correlation between the Fe L-edge, Mn L-edge, and N K-edge, imply a coupling between redox centers and an electron delocalization over the host framework.

Published
2023

10. Exploration of the Lithium Storage Mechanism in Monoclinic Nb2O5 as a Function of the Degree of Lithiation.

Author

Xue, Xilai, Asenbauer, Jakob, Eisenmann, Tobias, Lepore, Giovanni Orazio, d'Acapito, Francesco, Xing, Silin, Tübke, Jens, Mullaliu, Angelo, Li, Yueliang, Geiger, Dorin, Biskupek, Johannes, Kaiser, Ute, Steinle, Dominik, Birrozzi, Adele, and Bresser, Dominic

Subjects
LITHIATION, TRANSMISSION electron microscopy, X-ray absorption, CRYSTAL structure, X-ray spectroscopy
Abstract

Insertion‐type Nb2O5 is a promising candidate for high‐power lithium‐ion anodes. Among the various polymorphs, monoclinic Nb2O5 (H‐Nb2O5) is considered as one of the most promising materials. Herein, the impact of decreasing the lower cutoff potential, i.e., increasing the amount of lithium that is inserted into the crystal structure, from the commonly used 1.0 V versus Li+/Li to 0.8 V and even 0.01 V is explored, yielding reversible specific capacities of 260, 280, and 400 mAh g−1, respectively, at a specific current of 0.05 A g−1. Remarkably, such increase in capacity does not come along with a deterioration of the cycling stability—at least initially. In fact, the comprehensive investigation of the reaction mechanism via operando/ex situ X‐ray diffraction, operando/ex situ X‐ray absorption spectroscopy, ex situ high‐resolution transmission electron microscopy, and operando isothermal microcalorimetry reveals that the extension of the voltage range does not affect the crystal structure during the first couple of cycles, but there is a continuous evolution upon long‐term cycling. [ABSTRACT FROM AUTHOR]

Published
2024
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21. Layered Oxide Material as a Highly Stable Na‐ion Source and Sink for Investigation of Sodium‐ion Battery Materials.

Author

Wu, Fanglin, Li, Huihua, Diemant, Thomas, Mullaliu, Angelo, Zhang, Huang, and Passerini, Stefano

Subjects
LITHIUM titanate, NEGATIVE electrode, SODIUM ions, TRANSITION metal oxides, LITHIUM, STANDARD hydrogen electrode, IRON
Abstract

Investigating Na‐ion battery (SIB) materials is complicated by the absence of a well‐performing (reference) electrode material since sodium metal cannot be considered as a quasi‐reference electrode. Taking advantage of the activity of both Ni and Mn, herein, the P2‐type and Mn‐rich Na0.6Ni0.22Al0.11Mn0.66O2 (NAM) material, known to be an excellent positive electrode, is investigated as a negative electrode. To prove NAM stability as both positive and negative electrode, symmetric cells have been assembled without pre‐sodiation, which showed a reversible capacity of 73 mA h g−1 and a remarkable capacity retention of 82.6 % after 500 cycles. The outstanding cycling performance is ascribed to the high stability of the active material at both the highest and lowest Na‐ion storage plateaus and the rather limited electrolyte decomposition and solid‐electrolyte‐interphase (SEI) formation occurring. The long‐term stability of NAM at both electrodes enables its use as a "reference" electrode for the investigation of other positive and negative electrode materials for SIBs, resembling the role played by lithium titanate (LTO) and lithium iron phosphate (LFP) in LIBs. [ABSTRACT FROM AUTHOR]

Published
2024
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23. Beneficial impact of lithium bis(oxalato)borate as electrolyte additive for high‐voltage nickel‐rich lithium‐battery cathodes

Author

Wu, Fanglin, Mullaliu, Angelo, Diemant, Thomas, Stepien, Dominik, Parac-Vogt, Tatjana N., Kim, Jae-Kwang, Bresser, Dominic, Kim, Guk-Tae, and Passerini, Stefano

Subjects
Technology, ddc:600
Abstract

High-voltage nickel-rich layered cathodes possess the requisite, such as excellent discharge capacity and high energy density, to realize lithium batteries with higher energy density. However, such materials suffer from structural and interfacial instability at high voltages (>4.3 V). To reinforce the stability of these cathode materials at elevated voltages, lithium borate salts are investigated as electrolyte additives to generate a superior cathode-electrolyte interphase. Specifically, the use of lithium bis(oxalato)borate (LiBOB) leads to an enhanced cycling stability with a capacity retention of 81.7%. Importantly, almost no voltage hysteresis is detected after 200 cycles at 1C. This outstanding electrochemical performance is attributed to an enhanced structural and interfacial stability, which is attained by suppressing the generation of micro-cracks and the superficial structural degradation upon cycling. The improved stability stems from the formation of a fortified borate-containing interphase which protects the highly reactive cathode from parasitic reactions with the electrolyte. Finally, the decomposition process of LiBOB and the possible adsorption routes to the cathode surface are deduced and elucidated.

Published
2023

31. Comprehensive Approach to Investigate the De‐/Lithiation Mechanism of Fe‐Doped SnO2 as Lithium‐Ion Anode Material

Author

Asenbauer, Jakob, primary, Wirsching, Anna‐Lena, additional, Lang, Marcel, additional, Indris, Sylvio, additional, Eisenmann, Tobias, additional, Mullaliu, Angelo, additional, Birrozzi, Adele, additional, Hoefling, Alexander, additional, Geiger, Dorin, additional, Kaiser, Ute, additional, Schuster, Rolf, additional, and Bresser, Dominic, additional

Published
2022
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32. Synergistic Effect of Co and Mn Co-Doping on SnO2 Lithium-Ion Anodes

Author

Birrozzi, Adele, primary, Mullaliu, Angelo, additional, Eisenmann, Tobias, additional, Asenbauer, Jakob, additional, Diemant, Thomas, additional, Geiger, Dorin, additional, Kaiser, Ute, additional, Oliveira de Souza, Danilo, additional, Ashton, Thomas E., additional, Groves, Alexandra R., additional, Darr, Jawwad A., additional, Passerini, Stefano, additional, and Bresser, Dominic, additional

Published
2022
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38. Local interactions governing the performance of lithium- and manganese-rich cathodes

Author

Ministerio de Ciencia, Innovación y Universidades (España), Consejo Superior de Investigaciones Científicas (España), Helmholtz Association, Ali, Shehab E., Olszewski, Wojciech, Sorrentino, Andrea, Marini, Carlo, Kazzazi, Arefehsadat, Laszczynski, Nina, Birrozzi, Agnese, Mullaliu, Angelo, Passerini, Stefano, Tonti, Dino, Simonelli, Laura, Ministerio de Ciencia, Innovación y Universidades (España), Consejo Superior de Investigaciones Científicas (España), Helmholtz Association, Ali, Shehab E., Olszewski, Wojciech, Sorrentino, Andrea, Marini, Carlo, Kazzazi, Arefehsadat, Laszczynski, Nina, Birrozzi, Agnese, Mullaliu, Angelo, Passerini, Stefano, Tonti, Dino, and Simonelli, Laura

Abstract

The local structural and electronical transformations occurring along the first charge and discharge cycle of Li- and Mn-rich Li[Li0.2Ni0.16Mn0.56Co0.08]O2 cathode material have been characterized by X-ray absorption spectroscopy at several complementary edges. The irreversible spinel formation, occurring at the expenses of the cycling layered phase during the first charge, is quantified (about 10%) and spatially localized. The local strains induced by the Ni oxidation have been evaluated. They induce the formation of a low spin Mn3+ in the layered structure in parallel to the irreversible formation of the spinel phase in the particles bulk. The charge balance has been quantified for all the elements along the first charging cycle, confirming a reversible oxygen oxidation along the charge. Overall, these quantitative results provide an experimental basis for modeling aimed to control the structure and its evolution, for instance, hindering the spinel formation for the benefit of the material cycle life.

Published
2021

39. Soft X-ray Transmission Microscopy on Lithium-Rich Layered-Oxide Cathode Materials

Author

Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Helmholtz Association, Sorrentino, Andrea, Simonelli, Laura, Kazzazi, Arefehsadat, Laszczynski, Nina, Birrozzi, Agnese, Mullaliu, Angelo, Pereiro, Eva, Passerini, Stefano, Giorgetti, Marco, Tonti, Dino, Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Helmholtz Association, Sorrentino, Andrea, Simonelli, Laura, Kazzazi, Arefehsadat, Laszczynski, Nina, Birrozzi, Agnese, Mullaliu, Angelo, Pereiro, Eva, Passerini, Stefano, Giorgetti, Marco, and Tonti, Dino

Abstract

Energy-dependent full field transmission soft X-ray microscopy (TXM) is able to give a full picture at the nanometer scale of the chemical state and spatial distribution of oxygen and other elements relevant for battery materials, providing pixel-by-pixel absorption spectrum. We show different methods to localize chemical inhomogeneities in Li1.2Mn0.56Ni0.16Co0.08O2 particles with and without VOx coating extracted from electrodes at different states of charge. Considering the 3d(Mn,Ni)-2p(O) hybridization, it has been possible to discriminate the chemical state of Mn and Ni in addition to the one of O. Different oxidation states correspond to specific features in the O-K spectra. To localize sample regions with specific compositions we apply two different methods. In the first, the pixel-by-pixel ratios of images collected at different key energies clearly highlight local inhomogeneities. In the second, introduced here for the first time, we directly correlate corresponding pixels of the two images on a xy scatter plot that we call phase map, where we can visualize the distributions as function of thickness as well as absorption artifacts. We can select groups of pixels, and then map regions with similar spectral features. Core-shell distributions of composition are clearly shown in these samples. The coating appears in part to frustrate some of the usual chemical evolution. In addition, we could directly observe several further aspects, such as: distribution of conducting carbon; inhomogeneous state of charge within the electrode; molecular oxygen profiles within a particle. The latter suggests a surface loss with respect to the bulk but an accumulation layer at intermediate depth that could be assigned to retained O2.

Published
2021

40. Impact of Crystal Density on the Electrochemical Behavior of Lithium-Ion Anode Materials: Exemplary Investigation of (Fe-Doped) GeO2

Author

Eisenmann, Tobias, primary, Birrozzi, Adele, additional, Mullaliu, Angelo, additional, Asenbauer, Jakob, additional, Giuli, Gabriele, additional, Trapananti, Angela, additional, Olivi, Luca, additional, Moon, Hyein, additional, Geiger, Dorin, additional, Kaiser, Ute, additional, Passerini, Stefano, additional, and Bresser, Dominic, additional

Published
2021
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43. Comprehensive Approach to Investigate the De‐/Lithiation Mechanism of Fe‐Doped SnO2 as Lithium‐Ion Anode Material.

Author

Asenbauer, Jakob, Wirsching, Anna‐Lena, Lang, Marcel, Indris, Sylvio, Eisenmann, Tobias, Mullaliu, Angelo, Birrozzi, Adele, Hoefling, Alexander, Geiger, Dorin, Kaiser, Ute, Schuster, Rolf, and Bresser, Dominic

Subjects
DOPING agents (Chemistry), MOSSBAUER spectroscopy, ANODES, NUCLEAR magnetic resonance spectroscopy, TIN oxides
Abstract

Iron‐doped tin oxide (Sn0.9Fe0.1O2), and specifically carbon‐coated Sn0.9Fe0.1O2 (Sn0.9Fe0.1O2‐C) provides high reversible capacity and a reasonably low de‐/lithiation potential owing to the combined conversion and alloying mechanism. The initial (quasi‐)amorphization during the first lithiation, however, renders an in‐depth understanding of the reaction mechanism challenging. Herein, a comprehensive investigation via a set of highly complementary characterization techniques is reported, including operando X‐ray diffraction, ex situ 119Sn and 57Fe Mössbauer spectroscopy, ex situ 7Li NMR spectroscopy, operando isothermal microcalorimetry (IMC) of Li‖Sn0.9Fe0.1O2‐C coin cells, and electrochemical microcalorimetry of single Sn0.9Fe0.1O2‐C electrodes. The combination of these advanced techniques allows for detailed insights into the lithiation and delithiation mechanism and the potential determining processes, despite the (quasi‐) amorphous nature of the active material after the initial lithiation. [ABSTRACT FROM AUTHOR]

Published
2022
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