Reimuth, Christoph (2023)
Chemo-mechanical Simulation of the Influence of Dislocations in Lithium-ion Battery Materials.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00023865
Dissertation, Erstveröffentlichung, Verlagsversion
Kurzbeschreibung (Abstract)
Lithium-ion batteries (LIBs) represent the subject of rapidly growing research efforts due to their outstanding physical properties, such as high energy density, superior rate capability, and excellent cycling performance. These performance parameters of LIBs are governed by the ion diffusion process in the host electrode materials. The role of material heterogeneity and structural defects is one of the major research topics regarding the performance optimization of LIBs. In this work, a mechanically coupled diffusion model combined with finite element formulation is developed, where the dislocation is modeled by the regularized eigenstrain based on a non-singular continuum dislocation theory. The free energy density for the diffusion model was formulated as a function of the ion concentration, including the strain energy density. The ions were attributed with an eigenstrain representing the volume change upon ion intercalation. The model was applied to study the interaction between dislocations and diffusive ions. On the one hand, depending on the state of charge, the results show a redistribution of the ions respective to the dislocation stress field. On the other hand, the diffusing ions introduce a stress field, reducing the dislocation stress field. The simulation of potentiostatic and galvanostatic charging shows a substantial heterogeneity of ion concentration around the dislocation core but no overall alteration of the charging speed. Furthermore, the mechanically coupled diffusion model is extended to a phase separation model. The configurational mechanics is generalized for dislocations in the mechanically coupled diffusion model to compute driving forces on misfit dislocations. The driving forces on a dislocation are due to the strain originating from the lattice misfit and from the dislocation interaction with free surfaces, which can be described with the model of an image dislocation. An energy-based criterion for the stability of misfit dislocations in two-phase electrode particles is formulated. This allows computing the energy required to introduce a misfit dislocation into a particle and analyze the results to find a critical particle size for stable dislocations. The results show that the critical particle size is the smallest when the dislocation and interface are positioned in the center. The critical particle size also strongly depends on the dislocation core width implemented in the dislocation model.
Typ des Eintrags: | Dissertation | ||||
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Erschienen: | 2023 | ||||
Autor(en): | Reimuth, Christoph | ||||
Art des Eintrags: | Erstveröffentlichung | ||||
Titel: | Chemo-mechanical Simulation of the Influence of Dislocations in Lithium-ion Battery Materials | ||||
Sprache: | Englisch | ||||
Referenten: | Xu, Prof. Dr. Bai-Xiang ; Genenko, Prof. Dr. Yuri | ||||
Publikationsjahr: | 2023 | ||||
Ort: | Darmstadt | ||||
Kollation: | XVII, 126 Seiten | ||||
Datum der mündlichen Prüfung: | 6 März 2023 | ||||
DOI: | 10.26083/tuprints-00023865 | ||||
URL / URN: | https://tuprints.ulb.tu-darmstadt.de/23865 | ||||
Kurzbeschreibung (Abstract): | Lithium-ion batteries (LIBs) represent the subject of rapidly growing research efforts due to their outstanding physical properties, such as high energy density, superior rate capability, and excellent cycling performance. These performance parameters of LIBs are governed by the ion diffusion process in the host electrode materials. The role of material heterogeneity and structural defects is one of the major research topics regarding the performance optimization of LIBs. In this work, a mechanically coupled diffusion model combined with finite element formulation is developed, where the dislocation is modeled by the regularized eigenstrain based on a non-singular continuum dislocation theory. The free energy density for the diffusion model was formulated as a function of the ion concentration, including the strain energy density. The ions were attributed with an eigenstrain representing the volume change upon ion intercalation. The model was applied to study the interaction between dislocations and diffusive ions. On the one hand, depending on the state of charge, the results show a redistribution of the ions respective to the dislocation stress field. On the other hand, the diffusing ions introduce a stress field, reducing the dislocation stress field. The simulation of potentiostatic and galvanostatic charging shows a substantial heterogeneity of ion concentration around the dislocation core but no overall alteration of the charging speed. Furthermore, the mechanically coupled diffusion model is extended to a phase separation model. The configurational mechanics is generalized for dislocations in the mechanically coupled diffusion model to compute driving forces on misfit dislocations. The driving forces on a dislocation are due to the strain originating from the lattice misfit and from the dislocation interaction with free surfaces, which can be described with the model of an image dislocation. An energy-based criterion for the stability of misfit dislocations in two-phase electrode particles is formulated. This allows computing the energy required to introduce a misfit dislocation into a particle and analyze the results to find a critical particle size for stable dislocations. The results show that the critical particle size is the smallest when the dislocation and interface are positioned in the center. The critical particle size also strongly depends on the dislocation core width implemented in the dislocation model. |
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Status: | Verlagsversion | ||||
URN: | urn:nbn:de:tuda-tuprints-238659 | ||||
Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 500 Naturwissenschaften und Mathematik > 500 Naturwissenschaften | ||||
Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Mechanik Funktionaler Materialien |
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Hinterlegungsdatum: | 23 Jun 2023 12:04 | ||||
Letzte Änderung: | 26 Jun 2023 06:10 | ||||
PPN: | |||||
Referenten: | Xu, Prof. Dr. Bai-Xiang ; Genenko, Prof. Dr. Yuri | ||||
Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: | 6 März 2023 | ||||
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