Loho, Christoph (2018)
Advanced Chemical Vapor Deposition Methods for All-Solid-State, Conversion-Type and 3D Li-Ion Battery Concepts.
Technische Universität Darmstadt
Dissertation, Erstveröffentlichung
Kurzbeschreibung (Abstract)
The newly established CO2-laser assisted chemical vapor deposition (LA-CVD) is applied to research multicomponent Li-ion battery materials, which are very difficult to prepare with conventional CVD precursor delivery systems. The capabilities of LA-CVD to grow functional thin films for application in next generation Li-ion batteries, i.e., all-solid-state, conversion-type, and 3D architecture concepts, are assessed in comparison with aerosol assisted chemical vapor deposition (AA-CVD), which is another advanced precursor delivery method. The growth of high quality, well-performing battery materials is successfully achieved with both CVD techniques. AA-CVD allows for a more precise control over the stoichiometry of the films, exemplified by depositions of LiCoO2, LiCo1-xNixO2, and Li(Ni1/3Mn1/3Co1/3)O2 (NMC) cathodes. But with LA-CVD the microstructure of the films can be tailored between highly dense and porous providing more flexibility towards application. Both CVD processes make conformal coatings of 3D architectures possible with structure sizes down to several 10 μm (AA-CVD) and 1.5 μm (LA-CVD), thus have high potential for coatings in 3D battery concepts. Efforts are made to develop thin films of garnet-type oxide solid electrolytes due to their high Li-ion conductivity paired with a wide electrochemical stability window qualifying them for the use in all-solid-state batteries (ASSBs). It is found that AA-CVD is unsuited for the growth of garnet-type solid electrolytes, whereas LA-CVD is capable of growing garnet-type thin films of composition Li5La3Ta2O12 (LLTaO) and Li7La3Zr2O12 (LLZrO). The result that cubic LLTaO can be stabilized easier than cubic LLZrO via LA-CVD is exploited to study the influence of grain boundaries in fine-grained and coarse-grained LLTaO thin films. Furthermore, the chemical stability between LLTaO and Li on the atomic level is proven experimentally for the first time resolving a recent debate on their interfacial stability. Both CVD methods are well suited for the growth of conversion-type transition metal (TM) oxide anodes. By investigating the kinetics and degradation mechanisms of TM-oxide films (TM = Co, Ni, Mn) a clear correlation between microstructure and performance is found. Higher porosity and smaller structure size lead to increased rate capability and higher specific capacity. Therefore, TM-oxide thin film anodes with nanoparticulate microstructure grown by AA-CVD and LA-CVD bear great potential for application in conversion-type battery concepts. Having accomplished every battery component individually, model experiments on different garnet based ASSBs are pursued. Cycling a thin film battery based on LiCoO2 | LLTaO grown consecutively by LA-CVD failed, however, a hybrid cell with additional liquid electrolyte could be cycled successfully. Moreover, ASSBs combining pelletized LLZrO with a LiCoO2 thin film grown by LA-CVD, with and without interface modification by Nb, can be reversibly cycled at 25 °C with superior performance to the majority of literature reports on garnet based ASSBs. Several of the investigated Li-ion battery materials are grown for the first time via CVD such as thin films of LiNiO2, LiCo1-xNixO2 and NMC cathodes, LLTaO and LLZrO solid electrolytes as well as Ni- and Mn-oxide anodes. Besides, garnet-type LLTaO and LLZrO grown by LA-CVD and NiO grown by AA-CVD show best-in-class performances indicating the high quality of thin films grown by either method. Consequently, this dissertation demonstrates that the use of advanced CVD precursor delivery methods opens up a powerful playground for Li-ion battery applications in terms of material development, fundamental research, and realization of next generation Li-ion battery concepts.
Typ des Eintrags: | Dissertation | ||||
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Erschienen: | 2018 | ||||
Autor(en): | Loho, Christoph | ||||
Art des Eintrags: | Erstveröffentlichung | ||||
Titel: | Advanced Chemical Vapor Deposition Methods for All-Solid-State, Conversion-Type and 3D Li-Ion Battery Concepts | ||||
Sprache: | Englisch | ||||
Referenten: | Hahn, Prof. Dr. Horst ; Janek, Prof. Dr. Jürgen | ||||
Publikationsjahr: | 2018 | ||||
Ort: | Darmstadt | ||||
Datum der mündlichen Prüfung: | 6 Juli 2018 | ||||
URL / URN: | http://tuprints.ulb.tu-darmstadt.de/7577 | ||||
Kurzbeschreibung (Abstract): | The newly established CO2-laser assisted chemical vapor deposition (LA-CVD) is applied to research multicomponent Li-ion battery materials, which are very difficult to prepare with conventional CVD precursor delivery systems. The capabilities of LA-CVD to grow functional thin films for application in next generation Li-ion batteries, i.e., all-solid-state, conversion-type, and 3D architecture concepts, are assessed in comparison with aerosol assisted chemical vapor deposition (AA-CVD), which is another advanced precursor delivery method. The growth of high quality, well-performing battery materials is successfully achieved with both CVD techniques. AA-CVD allows for a more precise control over the stoichiometry of the films, exemplified by depositions of LiCoO2, LiCo1-xNixO2, and Li(Ni1/3Mn1/3Co1/3)O2 (NMC) cathodes. But with LA-CVD the microstructure of the films can be tailored between highly dense and porous providing more flexibility towards application. Both CVD processes make conformal coatings of 3D architectures possible with structure sizes down to several 10 μm (AA-CVD) and 1.5 μm (LA-CVD), thus have high potential for coatings in 3D battery concepts. Efforts are made to develop thin films of garnet-type oxide solid electrolytes due to their high Li-ion conductivity paired with a wide electrochemical stability window qualifying them for the use in all-solid-state batteries (ASSBs). It is found that AA-CVD is unsuited for the growth of garnet-type solid electrolytes, whereas LA-CVD is capable of growing garnet-type thin films of composition Li5La3Ta2O12 (LLTaO) and Li7La3Zr2O12 (LLZrO). The result that cubic LLTaO can be stabilized easier than cubic LLZrO via LA-CVD is exploited to study the influence of grain boundaries in fine-grained and coarse-grained LLTaO thin films. Furthermore, the chemical stability between LLTaO and Li on the atomic level is proven experimentally for the first time resolving a recent debate on their interfacial stability. Both CVD methods are well suited for the growth of conversion-type transition metal (TM) oxide anodes. By investigating the kinetics and degradation mechanisms of TM-oxide films (TM = Co, Ni, Mn) a clear correlation between microstructure and performance is found. Higher porosity and smaller structure size lead to increased rate capability and higher specific capacity. Therefore, TM-oxide thin film anodes with nanoparticulate microstructure grown by AA-CVD and LA-CVD bear great potential for application in conversion-type battery concepts. Having accomplished every battery component individually, model experiments on different garnet based ASSBs are pursued. Cycling a thin film battery based on LiCoO2 | LLTaO grown consecutively by LA-CVD failed, however, a hybrid cell with additional liquid electrolyte could be cycled successfully. Moreover, ASSBs combining pelletized LLZrO with a LiCoO2 thin film grown by LA-CVD, with and without interface modification by Nb, can be reversibly cycled at 25 °C with superior performance to the majority of literature reports on garnet based ASSBs. Several of the investigated Li-ion battery materials are grown for the first time via CVD such as thin films of LiNiO2, LiCo1-xNixO2 and NMC cathodes, LLTaO and LLZrO solid electrolytes as well as Ni- and Mn-oxide anodes. Besides, garnet-type LLTaO and LLZrO grown by LA-CVD and NiO grown by AA-CVD show best-in-class performances indicating the high quality of thin films grown by either method. Consequently, this dissertation demonstrates that the use of advanced CVD precursor delivery methods opens up a powerful playground for Li-ion battery applications in terms of material development, fundamental research, and realization of next generation Li-ion battery concepts. |
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URN: | urn:nbn:de:tuda-tuprints-75775 | ||||
Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 500 Naturwissenschaften und Mathematik > 500 Naturwissenschaften 500 Naturwissenschaften und Mathematik > 530 Physik 500 Naturwissenschaften und Mathematik > 540 Chemie 600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften und Maschinenbau |
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Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Gemeinschaftslabor Nanomaterialien |
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Hinterlegungsdatum: | 22 Jul 2018 19:55 | ||||
Letzte Änderung: | 22 Jul 2018 19:55 | ||||
PPN: | |||||
Referenten: | Hahn, Prof. Dr. Horst ; Janek, Prof. Dr. Jürgen | ||||
Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: | 6 Juli 2018 | ||||
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