Book/Dissertation / PhD Thesis

FZJ-2023-05515

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Na5YSi4O12-type Na+ superionic conductors for solid-state batteries

Yang, A. (Corresponding author)FZJ*

2023
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

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Please use a persistent id in citations: doi:10.34734/FZJ-2023-05515

Abstract: The development of high-performance solid-state batteries (SSBs) has gained increasing attention in recent years as a promising alternative to conventional liquid electrolyte batteries. In this context, the Na5YSi4O12- type (NYS) Na+ superionic conductors have emerged as potential electrolyte candidates due to their high Na+ ionic conductivity and stability in solid-state Na batteries (SSSBs). This thesis investigates the synthesis, characterization, and electrochemical properties of NYS-type Na+ superionic conductors, focusing on their applicability in large-scale fabrication as well as in SSBs and the development of novel compositions with higher ionic conductivity. The background of the work is introduced in the first two chapters, followed by an explanation of the preparation and characterization methods applied. The results and discussion are divided into three main parts: First, tape-casting of thin NYS sheets using aqueous slurries has been developed. The microstructure, crystal structure, electrochemical performance and mechanical properties of the as-prepared NYS tapes have been investigated. After sintering, the obtained NYS tapes had high crystalline purity, dense microstructure (relative density > 90%), and favorable mechanical properties (hardness H of 2 GPa andYoung’s modulus E of 45 GPa). The NYS tapes showed a total ionic conductivity of 1.0 mS cm‒1 at room temperature (RT), a low total activation energy of 0.30 eV, and a wide electrochemical stability window of over 8 V. The critical current density (CCD) of NYS tape against Na metal electrodes reached 2.2 mA cm‒ 2 and the galvanostatic cycling time was over 280 h at 0.8 mA cm‒2 and 0.8 mAh cm‒2. This work not only highlights the potential of the scarcely studied silicate-based NYS ionic conductor as a functional separator but also presents a cost-efficient and eco-friendly continuous fabrication using the aqueous tape casting technique, thus is expected to boost the practical application of NYS as a solid-state electrolyte (SSE) in SSSBs.

Note: Dissertation, RWTH Aachen University, 2023

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Contributing Institute(s):

1. Werkstoffsynthese und Herstellungsverfahren (IEK-1)

Research Program(s):

1. 899 - ohne Topic (POF4-899) (POF4-899)

Appears in the scientific report 2023

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