@misc{SieberDuckeRietigetal., author = {Sieber, Tim and Ducke, Jana and Rietig, Anja and Langner, Thomas and Acker, J{\"o}rg}, title = {Recovery of Li(Ni0.33Mn0.33Co0.33)O2 from Lithium-Ion Battery Cathodes: Aspects of Degradation}, series = {Nanomaterials}, volume = {9}, journal = {Nanomaterials}, number = {2}, issn = {2079-4991}, doi = {10.3390/nano9020246}, pages = {246 -- 259}, abstract = {Nickel-manganese-cobalt oxides, with LiNi0.33Mn0.33Co0.33O2 (NMC) as the most prominent compound, are state-of-the-art cathode materials for lithium-ion batteries in electric vehicles. The growing market for electro mobility has led to a growing global demand for Li, Co, Ni, and Mn, making spent lithium-ion batteries a valuable secondary resource. Going forward, energy- and resource-inefficient pyrometallurgical and hydrometallurgical recycling strategies must be avoided. We presented an approach to recover NMC particles from spent lithium-ion battery cathodes while preserving their chemical and morphological properties, with a minimal use of chemicals. The key task was the separation of the cathode coating layer consisting of NMC, an organic binder, and carbon black, from the Al substrate foil. This can be performed in water under strong agitation to support the slow detachment process. However, the contact of the NMC cathode with water leads to a release of Li+ ions and a fast increase in the pH. Unwanted side reactions may occur as the Al substrate foil starts to dissolve and Al(OH)3 precipitates on the NMC. These side reactions are avoided using pH-adjusted solutions with sufficiently high buffer capacities to separate the coating layer from the Al substrate, without precipitations and without degradation of the NMC particles.}, language = {en} } @incollection{RietigAcker, author = {Rietig, Anja and Acker, J{\"o}rg}, title = {Ressourcensicherung durch Recycling von Sekund{\"a}rrohstoffen}, series = {Systemwissen f{\"u}r die vernetzte Energie- und Mobilit{\"a}tswende}, booktitle = {Systemwissen f{\"u}r die vernetzte Energie- und Mobilit{\"a}tswende}, edition = {1. Auflage}, publisher = {Vereinigung f{\"u}r Betriebliche Bildungsforschung e.V.}, address = {Berlin}, isbn = {978-3-9816861-7-3}, pages = {170 -- 181}, language = {de} } @misc{RietigLangnerAcker, author = {Rietig, Anja and Langner, Thomas and Acker, J{\"o}rg}, title = {A revised model of silicon oxidation during the dissolution of silicon in HF/HNO₃ mixtures}, series = {Physical chemistry, chemical physics}, volume = {21}, journal = {Physical chemistry, chemical physics}, issn = {1463-9076}, doi = {10.1039/c9cp04429a}, pages = {22002 -- 22013}, abstract = {The stoichiometry of wet chemical etching of silicon in concentrated HF/HNO₃ mixtures was investigated. The formation of nitrogen species enriched in the etching mixture and their reactivity during the etching process was studied. The main focus of the investigations was the comprehensive quantification of the gaseous reaction products using mass spectrometry. Whereas previously it could only be speculated that nitrogen was a product, its formation was detected for the first time. The formation of hydrogen, N₂, N₂O and NH₄⁺ showed a dependence on the etching bath volume used, which indicates the formation of nitrogen compounds by side reactions. Simultaneously, the ratio of the nitrogen oxides, NO and NO₂, formed decreases with increasing etching bath volume, while nitric acid consumption increases, so that the formation of NO₂ could also be identified as a side reaction. Based on the stoichiometries obtained, a new reaction scheme for the reduction of nitric acid during etching in HF/HNO₃ mixtures and an electron balance for the oxidation of silicon is presented.}, language = {en} } @misc{SieberRietigDuckeetal., author = {Sieber, Tim and Rietig, Anja and Ducke, Jana and Acker, J{\"o}rg}, title = {Direkte Feststoffanalyse von Hauptkomponenten in Kathodenmaterialien von Lithiumbatterien mittels HRCS-GF-AAS}, series = {Colloquium Analytische Atomspektroskopie - CANAS 2019, Book of Abstracts}, volume = {2019}, journal = {Colloquium Analytische Atomspektroskopie - CANAS 2019, Book of Abstracts}, editor = {Vogt, Carla}, edition = {1. Auflage}, publisher = {TU Bergakademie Freiberg}, address = {Freiberg}, pages = {S1/4}, abstract = {Zur Bestimmung der metallischen Hauptkomponenten in Lithium-Batterie-Kathodenmaterialien ist der nasschemische Aufschluss mit anschließender ICP-OES-Analyse oft das Mittel der Wahl. Da dieses Verfahren jedoch recht zeitaufwendig ist und den Einsatz starker S{\"a}uren erfordert, wurde eine Methode zur direkten Feststoffanalyse mittels HRCS-GF-AAS (high resolution continuum source graphit furnace atom absorption spectrometry) nach dem STPF-Konzept (stabilized temperature platform furnace) entwickelt. Die hohen Analytkonzentrationen erfordern dabei die Messung auf den vergleichsweise wenig intensiven Linien Li = 323,2657 nm, Ni = 294,3912 nm, Mn = 321,6945 nm und Co= 243,5823 nm. Zus{\"a}tzlich wird das Probenmaterial einer Feststoffverd{\"u}nnung mit matrixverwandten Komponenten unterzogen. Die Verd{\"u}nnung senkt zum einen die Konzentration und die Gefahr der Verschleppung der Analyten und beg{\"u}nstigt zum anderen die Freigabe des Analyten aus der Probenmatrix. Durch Aufnahme von Extinktions-Zeit-Verl{\"a}ufen im Temperaturbereich von 200 - 2600 °C konnten die Freisetzungstemperaturen f{\"u}r jeden Analyten bestimmt werden. Nach anschließenden Optimierungen der Pyrolyse- und Atomisierungstemperaturen wurde mithilfe der Einzeloxide f{\"u}r jeden Analyten die Linearit{\"a}t des Messsignals gepr{\"u}ft und der Arbeitsbereich festgelegt. Durch Vermessung von variierenden Oxidmischungen und Mischoxiden, sowie Zusatz m{\"o}glicher weiterer Interferenten, wie dem Bindermaterial PVDF wurden Spezifit{\"a}t, Selektivit{\"a}t und Robustheit der Methode {\"u}berpr{\"u}ft. Abschließend erfolgte anhand realer Proben (Recyclinggut aus Lithium-Batterie-Kathoden) ein Vergleich zwischen den Ergebnissen der direkten Feststoffanalyse mittels HRCS-GF-AAS und dem bereits etablierten Verfahren der ICP-OES Analyse nach nasschemischem Aufschluss. Nach umfangreicher Methodenentwicklung kann ein Verfahren der direkten Feststoffanalyse von Recylinggut aus Kathodenmaterialien von Lithium-Ionen-Batterien mittels HRCS-GF-AAS bereitgestellt werden, das eine schnelle und pr{\"a}zise Analyse der Hauptkomponenten Li, Ni, Mn und Co erlaubt.}, language = {de} } @misc{AckerSieberDuckeetal., author = {Acker, J{\"o}rg and Sieber, Tim and Ducke, Jana and Langner, Thomas and Rietig, Anja}, title = {Degradation effects on Li(Ni0.33Mn0.33Co0.33)O2 in the recovery of lithium battery cathodes}, series = {Advanced Lithium Batteries for Automobile Applications - ABAA 12, Book of Abstracts}, journal = {Advanced Lithium Batteries for Automobile Applications - ABAA 12, Book of Abstracts}, edition = {1. Auflage}, publisher = {Zentrum f{\"u}r Sonnenenergie- und Wasserstoff-Forschung Baden-W{\"u}rttemberg}, address = {Ulm}, pages = {28}, abstract = {The compound Li(Ni0.33Mn0.33Co0.33)O2 (NMC) is the state-of-the-art lithium-ion battery cathode material. Due to the increasing demand NMC is of crucial economically importance for the worldwide emerging market of electromobility. Recycling of end-of-life lithium-ion batteries to recover NMC, in particular of batteries from automotive vehicles, is one future strategy to save costs and to become more independent from the supply of the essential elements Co and Mn. Several concepts for NMC recycling from lithium-ion batteries are based on wet-chemical process steps, in particular, to separate the NMC containing cathode layer from the underlying metal foil. However, NMC is very sensitive against the attack by water and reagents that are added to promote the separation process. The present study deals with the wet-chemical recycling of NMC using aqueous reagent solutions in a under varying process conditions. The recovered NMC samples are characterized in order to study the ongoing degradation at the surface of the NMC particles. In particular, two major degradation pathways are identified: (i) a preferential loss of lithium and nickel and (ii) the formation of passivation layers due to unwanted side reactions. DRIFT measurements are performed to study the NMC surface species after the recovery processes. SEM/EDX mappings are used to detect changes in the chemical composition in the surface region of the chemically treated NMC particles. Finally, a detailed study of the changes in the chemical state at the NMC particle surface is done by Raman microscopy by means of the deconvolution of the recorded spectra into their A1G component (representing the metal-oxide phonons) and into the Eg component (representing the oxide-metal-oxide phonons). As result of this study, the consequences of different wet-chemical process conditions on the quality of the recovered NMC material are discussed.}, language = {en} }