On improvements of sodium manganese oxide materials as sodium-ion battery cathode

• Main Author: Bucher, Nicholas Joachim
• Other Authors: Maria-Elisabeth Michel-Beyerle
• Format: Theses and Dissertations
• Language: English
• Published: 2018
• Subjects: DRNTU::Engineering::Materials::Energy materials
• Online Access: https://hdl.handle.net/10356/88417; http://hdl.handle.net/10220/45953
• Institution: Nanyang Technological University

Mainly due to potential cost advantages sodium-ion batteries have the potential to become an alternative to lithium-ion batteries. In this work strategies to improve cycling stability of the cathode material P2-NaxMnO2 are presented. Cobalt-doping on the order of 10% leads to a suppression of structural changes, resulting in improved cyclability, and enhanced Na+ diffusion kinetics. Moreover, capacity and cyclability can be increased by an optimization of the morphology. A combination of both strategies leads to a material with comparably best discharge capacity and cycling stability. Natrium-Ionen-Batterien gelten hauptsächlich aufgrund potenzieller Kostenvorteile als mögliche Alternative zu Lithium-Ionen-Batterien. Diese Arbeit beschreibt Strategien zur Verbesserung der Zyklenstabilität von P2-NaxMnO2 als Kathodenmaterial. Eine ~10%ige Cobalt-Substitution bewirkt eine Unterdrückung von Strukturumwandlungen und eine Verbesserung der Na+-Diffusion. Des Weiteren kann die Kapazität und Zyklenstabilität durch eine Optimierung der Morphologie verbessert werden. Die Kombination beider Strategien vereint die jeweiligen Vorteile und führt zu einem Material mit hoher Kapazität und vergleichsweise bester Zyklenstabilität. This doctoral thesis is the cumulative integration of the scientific publications resulting from my work as a research associate at TUM CREATE. After a brief overview of different battery technologies, sodium-ion batteries are described in detail, followed by a description of the main experimental methods employed in this work. Subsequently, my four scientific publications, as well as one further publication in which my contribution was crucial, are presented. The thesis is concluded with a discussion of the presented results.