Enabling Ambient Sodium-Sulfur Batteries

Ambient sodium-sulfur batteries exploit the high energy electrochemical reaction of the globally abundant elements. However, these batteries are not yet realized due to their complex conversion reactions. Five groups of distinct expertise at US Naval Research Laboratory are combining to address fundamental knowledge gaps and a demonstrate a commercially viable system. We utilize unique in-situ spectroscopy and optical microscopy to better understand the fundamentals of the reaction. These findings inform electrolyte component selection and electrode design. Glassy-blends of chalcogens, previously explored for infrared optics, demonstrate distinct discharge mechanism that limits undesirable polysulfide formation. Finally, electrode design of the sulfur cathode is supported by a novel carbon nanofoam paper (CNFP) developed at NRL, which had tunable porosity, surface area, thickness, and sulfur loading. This platform demonstrates high areal capacity (&gt;4 mAh/cm2) and impressive capacity retention. Combining these findings, we demonstrate the scalability of this cathode in a lab-scale pouch prototype, accompanied by a metallic sodium anode, and sandwiched with spectroscopy-informed electrolyte. <br/>1.Deblock, R.H.; Lefler, M..J.; Neale, Z.G.; Love, C.T.; Long, J.W.; Carter, R.; Optical and X-ray Absorption Interrogation of Selenium-based Re-dox in Li-S_xSe_y batteries, <i>Energy Advances</i>, <b>2024</b>,3, 424-429.<br/>2.Neale, Z.G.; Lefler, M.J.; Long, J.W.; Rolison, D.R.; Sassin, M.B.; <b>Carter, R</b>.; Freestanding Carbon Nanofoam Papers with Tunable Porosity as Lithium-Sulfur Battery Cathodes. <i>Nanoscale,</i> <b>2023</b>, 15, 16924-16932.