One-Step Synthesis of a Highly Conductive Glassy Sodium Solid Electrolyte

Islamiyat Ojelade, Erica Truong, Ifeoluwa Oyekunle, Tej Poudel, Thillina Nadeemali Dikella, Yudan Chen, Yan-Yan Hu.

Florida State University

Na-ion solid electrolytes (SE) offer promising prospects for next-generation energy storage devices due to their inherent advantages, including improved safety and abundance of sodium resources. However, challenges remain in enabling efficient ion transport for high-power density. This work reports a novel sodium solid electrolyte composite, Na₂O-NaTaCl₆, synthesized via a one-step synthesis method. Remarkably, we achieved a high ionic conductivity of 4.41 mS/cm with only 4 hours of mechanochemical milling. Importantly, the achieved conductivity of Na₂O-NaTaCl₆ surpassed that of NaTaCl₆ synthesized under similar conditions by more than one order of magnitude. Using XRD and SSNMR characterization techniques, the presence of Na₂O as a glass former was found to amorphized the crystalline structure of NaTaCl₆, resulting in a highly glassy material. This structural modification facilitated enhanced Na⁺-ion migration, leading to high ionic conductivity and relatively favorable activation energy of 0.29 eV. In addition, the composite material exhibited a relatively low electronic conductivity of 6.72 x 10^-10 S/cm. This discovery holds significant implications for energy-efficient materials, paving the way for advancements in sodium-ion battery technology and contributing to the development of sustainable energy storage solutions.