| Title: |
Optimization, development and understanding of cation-disordered rocksalt materials as positive electrode for high-energy Li-ion batteries ; Optimisation, développement et compréhension de matériaux d'électrode positive pour batteries Li-ion de structure type NaCl désordonnée pour application haute énergie |
| Authors: |
Cogniard, Mathieu |
| Contributors: |
Laboratoire d'Innovation pour les Technologies des Energies Nouvelles et les nanomatériaux (LITEN / CEA-DES); CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)); Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de L'Energie Solaire (INES); Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS); Université Grenoble Alpes 2020-.; Jean-François Colin; Yohan Biecher |
| Source: |
https://theses.hal.science/tel-05385940 ; Autre. Université Grenoble Alpes [2020-.], 2025. Français. ⟨NNT : 2025GRALI041⟩. |
| Publisher Information: |
CCSD |
| Publication Year: |
2025 |
| Collection: |
Université Savoie Mont Blanc: HAL |
| Subject Terms: |
Mn-Rich; Disordered Rocksalt; Li-Rich; Batteries; Li-Ion Cathodes; Désordonnés types NaCl; [CHIM.OTHE]Chemical Sciences/Other |
| Description: |
This thesis focuses on the material Li2MnO2F as a positive electrode in Li-ion batteries. It delivers an experimental reversible capacity of about 300 mAh·g-1, and a gravimetric energy density close to 900 Wh·kg-1, but the significant drop in performance during cycling limits its application.The degradation mechanisms of the material were identified through an X-ray Absorption Spectroscopy (XAS) study. The use of chemometric analysis techniques allowed for the separation and quantification of the anionic and cationic contributions to the capacity, particularly during the first cycle. The aging of the material occurs in two stages: an irreversible oxidation of oxygen initially, followed by the limitation of the electrochemical activity of the manganese due to the dissolution of the active material, corrosion of the current collector, and an increase in interfaces impedance. In particular, the material's surface becomes resistive during cycling probably due to a cationic densification mechanism linked to manganese migration and the formation of oxygen vacancies. The degradation of the electrolyte at high potential is significant, and CO2 is released in substantial amounts during each cycle due to the oxidation of ethylene carbonate, contributing to the formation of resistive species on the surface of the electrodes. The high reactivity of the interfaces is also exacerbated by the need to nanostructure the material to compensate for its low intrinsic conductivity, therefore increasing its specific surface area and reducing the volumetric density of the electrodes.Several solutions to these issues have been explored while dealing with the material's metastability and air sensitivity. The material's morphology was optimized through ball-milling techniques and spray drying, in order to form spherical and dense secondary particles, a goal that was achieved, but without improving electrochemical performance. However, the performance was improved by modifying the carbonate electrolyte with the addition of specific ... |
| Document Type: |
doctoral or postdoctoral thesis |
| Language: |
French |
| Relation: |
NNT: 2025GRALI041 |
| Availability: |
https://theses.hal.science/tel-05385940; https://theses.hal.science/tel-05385940v1/document; https://theses.hal.science/tel-05385940v1/file/COGNIARD_2025_archivage.pdf |
| Rights: |
info:eu-repo/semantics/OpenAccess |
| Accession Number: |
edsbas.4D41ACB6 |
| Database: |
BASE |