@misc{MeissnerEfimovaSchmidt, author = {Meißner, Andr{\´e} and Efimova, Anastasia and Schmidt, Peer}, title = {Impacts of TGA furnace parameters for prediction of long-term thermal stability of ionic liquids}, series = {Thermochimica Acta}, volume = {704}, journal = {Thermochimica Acta}, doi = {10.1016/j.tca.2021.178917}, pages = {178917-1 -- 178917-7}, abstract = {The concept of maximum operation temperature is established for the prediction of the time dependent thermal stability of ionic liquids based on kinetic evaluation of thermogravimetric analysis. The influence of the furnace control parameters on the maximum operation temperature (MOT) is shown using the example of 1-methyl-3-propylimidazolium iodide ([C3C1im]I) with respect to three different parameter sets of a programmed proportional integral derivative (PID) controller of the TGA. Kinetics of thermal decomposition of [C3C1im]I have been investigated with the implementation of an improved kinetic model. The activation energy obtained using the Kissinger-Akahira-Sunose equation showed variations apparently due to the decomposition degree. The model compound is decomposed by a one-step kinetics, which results from pseudo zero order relationship of the activation energy to the conversion rate. The activation energy, pre-exponential factor, and the activation energy are strongly dependent on the parameters of TGA furnace controller.}, language = {en} } @inproceedings{MeissnerAcker, author = {Meißner, Andr{\´e} and Acker, J{\"o}rg}, title = {Raman spectroscopic study on the formation of Cu3Si}, series = {9th European Silicon Days, 9-12 September 2018, Saarbr{\"u}cken, Germany, Book of abstracts}, booktitle = {9th European Silicon Days, 9-12 September 2018, Saarbr{\"u}cken, Germany, Book of abstracts}, editor = {Scheschkewitz, David and Kickelbick, Guido}, publisher = {Universit{\"a}t des Saarlandes}, address = {Saarbr{\"u}cken}, abstract = {The term "direct synthesis" is defined in the literature as the reactions between silicon and methyl chloride, hydrogen chloride and other reagents like chlorobenzene and ethyl chloride to yield various alkyl- or aryl substituted chlorosilanes.[1] These reactions have two features in common: (1) The reactivity of silicon - in terms of reaction start temperature, reaction rate and silane product distribution - is originated and controlled by the interaction with metals. (2) The reaction is fully under kinetic control since the formed silanes are the thermodynamically least stable products in the system Si-H-Cl-C.[2] Several authors consider Cu3Si as the catalytically active phase in the direct synthesis. It is assumed, that CuCl formed under the conditions of the direct synthesis reacts with Si according to Eq. 1 and 2 to yield Cu3Si.[1] (1) and (2) The present work describes a Raman microscopic study of the reaction of Si with Cu and CuCl with special emphasize given to the identification of the Cu3Si phase and the processes occurring in the surrounding bulk Si. There is one pathway in which a solid state reaction[3] between Si and CuCl leads to a massive nucleation of Cu3Si exactly at the position of the Si/CuCl solid-solid interface. The nucleation of Cu3Si creates such an enormous lattice strain so that several high-pressure modifications of Si can be identified at the reaction site and around. The second reaction pathway is controlled by a gas phase transport of CuCl at low temperatures. This transport pathway leads to a spread of Cu in nearest neighborhood close to the CuCl particles as well to a long range transport leading to a nucleation of microscopic Cu3Si precipitates away from the CuCl particles. Further studies on the reactivity of the Cu3Si containing reaction sites were performed and will be discussed in the presentation.}, language = {en} } @misc{MarkowskiArellanoGarciaMeissneretal., author = {Markowski, Jens and Arellano-Garcia, Harvey and Meissner, Andr{\´e} and Acker, J{\"o}rg}, title = {Comparative studies on the quality of recovered secondary graphites from the recycling of lithium-ion traction batteries}, series = {Sustainable Minerals}, journal = {Sustainable Minerals}, publisher = {Mining Engineering}, address = {Falmouth (UK)}, abstract = {Automotive technology is increasingly determined by drives based on electric motors in combination with batteries. The lithium-ion traction battery is a storage medium that combines high electrical efficiency with compact dimensions and relatively low weight. For the recycling of the cathode coatings (esp. Ni, Mn, Co) and peripheral battery components a variety of recycling options already exist. The graphite coating of the anodes has hardly been the focus of research activities to date. State of the art is currently the melting of the complete Copper-anode foils including graphite coating, whereby the graphite contributes only as a carbon carrier to the recycling of the copper. Separation and reuse of the very high-quality graphite on an industrial scale has not yet taken place. At the BTU, a methodology has been developed, with which recovered anode graphites from traction batteries can be comprehensively characterised chemically and mechanically-physically. On this basis, targeted preparation for secondary applications is possible. The secondary graphites achieve a quality that allows them to be reused as second-use anode material and for other applications.}, language = {en} } @misc{KlepelUtgenanntVormelchertetal., author = {Klepel, Olaf and Utgenannt, Stephan and Vormelchert, Carolin and K{\"o}nig, Mark and Meißner, Andr{\´e} and Hansen, Felix and B{\"o}lte, Jens-Henning Ingo Holger and Sieber, Tim and Heinemann, Robert and Bron, Michael and Rokicinska, Anna and Jarczewski, Sebastian and Kustrowski, Piotr}, title = {Redox catalysts based on amorphous porous carbons}, series = {Microporous Mesoporous Materials}, volume = {323}, journal = {Microporous Mesoporous Materials}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2021.111257}, pages = {12}, language = {en} } @misc{MeissnerSieberAcker, author = {Meißner, Andr{\´e} and Sieber, Tim and Acker, J{\"o}rg}, title = {Lattice strain and phase transformations in silicon introduced by the precipitation of Cu3Si}, series = {Silicon for the Chemical and Solar Industry XV}, journal = {Silicon for the Chemical and Solar Industry XV}, editor = {Andresen, Birger and Rong, Harry and Tangstad, Merete and Tveit, Halvard and Page, Ingrid}, publisher = {The Norwegian University of Science and Technology}, address = {Trondheim}, isbn = {978-82-997357-9-7}, pages = {47 -- 56}, abstract = {The reaction of Si with CuCl was studied by a combination of Raman microscopy, confocal microscopy and SEM-EDX. Two reaction pathways were observed to proceed at the same time. The first one is a solid state reaction between Si and Cu or CuCl that leads to a massive nucleation of Cu3Si exactly at the interfacial contacts between CuCl and Si. This study shows how the presence of the Cu3Si phase can be clearly identified and distinguished from areas simply covered with copper by means of Raman microscopic measurements. The second reaction pathway identified proceeds via a short-range gas phase transport of CuCl at low temperatures. The immediate reaction of the transported CuCl to the Si surface causes the massive spread of Cu in the close neighborhood around the CuCl source particles, however, without a nucleation of Cu3Si. The nucleation of Cu3Si precipitates and the short-range transport of CuCl have a tremendous impact on the underlying Si matrix. Tensile- and compressive-strained Si are generated in the immediate vicinity of the precipitates and at their interface to the surrounding silicon. Indications of high-pressure modifications of Si were found. Those areas of the Si surface which are affected by the short-range transport of CuCl and covered with low concentrations of copper exhibit a significant tensile strain. As recently shown, tensile and compressive strain in Si have a significant impact on the reactivity of Si. It might be assumed that Cu3Si-induced lattice strain in Si affects the reactivity of Si in the Direct Reactions in a similar matter.}, language = {en} }