Sodium ion conducting ceramics for sodium ion batteries
Naqash, Sahir; Guillon, Olivier (Thesis advisor); Schneider, Jochen Michael (Thesis advisor)
Jülich : Forschungszentrum Jülich GmbH, Zentralbibliothek, Verlag (2019)
Book, Dissertation / PhD Thesis
In: Schriften des Forschungszentrums Jülich. Reihe Energie & Umwelt / Energy & environment 451
Page(s)/Article-Nr.: 1 Online-Ressource (vii, 134 Seiten) : Illustrationen, Diagramme
Dissertation, RWTH Aachen University, 2018
The overwhelming demand of energy storage technologies has forced the scientific community to look beyond the commercially available options such as lithium ion batteries. As one of a potential alternative, sodium ion battery technology works in a similar way but provides the advantage of abundant and readily available raw materials at low cost. In addition, the lithium ion batteries, so far, are commercially available only with a liquid electrolyte. The electrolyte material in liquid state poses serious safety concerns, in case there is a leakage causing a short circuit and thermal runaway. Therefore an all-solid-state approach is one way to improve the safety issues of state-of-the-art batteries. This work is performed to develop sodium ion-conducting ceramics that can be used in all-solid-state sodium ion batteries. Among several available options, the NASICON-type materials were selected because these types of materials are known to produce highly conductive ceramics and their conductivity in the best case has reached 4 mS cm-1. Therefore, this work focuses on the materials and processing aspects of these sodium ion-conducting materials. It can be is divided into two sections: 1) synthesis & processing and 2) materials design and composition. In the first part, main focus is on synthesis and processing of original NASICON material Na3Zr2Si2PO12. First, a solution-assisted solid state reaction synthesis route for producing Na3Zr2Si2PO12 is reported and compared with the so-called Pechini synthesis method. Secondly, Na3Zr2Si2PO12 is processed applying different sintering conditions to control its microstructure to better understand the microstructure-conductivity relationship of the material. In the second part, the focus is on the materials design and composition by modifying the NASICON chemistry. This is achieved by substituting suitable cations into the NASICON structure. Furthermore, an attempt was made to reduce the processing temperature of NASICON materials by defining a series of compositions, so-called glass-NASICON composites, towards the low melting composition in the quaternary phase diagram of Na2O-SiO2-ZrO2 and P2O5. The objective is to utilize the conduction properties of NASICON and low melting point of sodium-containing glasses to produce a material with sufficient Na+ ion conductivity and reduced processing temperature (< 1000 °C). This would then be used as electrolyte material for fabricating an all-solid state Na+ battery.