Symposium EN08: Materials Design and Discovery for Next-Generation Energy Storage Systems
December 03, 2024
Miaofang Chi, Duke University, Oak Ridge National Laboratory
Microscopic Insights into Enhancing Mechanical Properties and Ionic Conductivity in Sodium Solid Electrolytes
Written by Jun Meng
Solid-state sodium batteries are emerging as safer, more sustainable, and cost-effective alternatives to traditional lithium-ion systems. In today’s presentation, Miaofang Chi from Duke University and Oak Ridge National Laboratory focused on sodium zirconium phosphate (NaSICON) electrolytes, uncovering the microscopic factors that influence their mechanical properties, ionic conductivity, and stability.
Chi highlighted the beauty of NaSICON’s versatile crystal structure, which features structural flexibility and allows for doping with metals or non-metals, making it an attractive candidate for energy storage systems. However, challenges persist, particularly in redox flow battery applications, where structural changes and membrane cracking occur after 7 days of operation in solution.
Understanding the degradation mechanisms is key. With advanced electron microscopy, Chi revealed that NaSICON exhibits a complex multiphase structure, consisting of crystalline and amorphous phases with zirconium oxide (ZrOx) impurities. Chi’s study revealed that cracks predominantly originate from large ZrOx grains formed using conventional synthesis methods, and the amorphous regions contribute to structural instability and mechanical weakness. Synthesis methods were shown to be critical in overcoming these limitations. The solid-state assisted self-redox (SA-SSR) method, combined with hot pressing, emerged as a key approach, yielding a uniform morphology, higher crystalline content, and significantly improved ionic conductivity. These results underscore the importance of optimizing synthesis methods and employing high-resolution characterization techniques to mitigate microcracking and enhance structural stability.
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