Interfacial Engineering with a Nanoparticle-Decorated Porous Carbon Structure on β″-Alumina Solid-State Electrolytes for Molten Sodium Batteries
Minyuan M. Li, Shalini Tripathi, Evgueni Polikarpov, Nathan Canfield, Kee Sung Han, J. Mark Weller, Edgar C. Buck, Mark Engelhard, David Reed, Vincent Sprenkle, Guosheng Li
Abstract
We present a novel anode interface modification on the β″-alumina solid-state electrolyte that improves the wetting behavior of molten sodium in battery applications. Heat treating a simple slurry, composed only of water, acetone, carbon black, and lead acetate, formed a porous carbon network decorated with PbOx (0 ≤ x ≤ 2) nanoparticles between 10 and 50 nm. Extensive performance analysis, through impedance spectroscopy and symmetric cycling, shows a stable, low-resistance interface for close to 6000 cycles. Furthermore, an intermediate temperature Na–S cell with a modified β″-alumina solid-state electrolyte could achieve an average stable cycling capacity as high as 509 mA h/g. This modification drastically decreases the amount of Pb content to approximately 3% in the anode interface (6 wt % or 0.4 mol %) and could further eliminate the need for toxic Pb altogether by replacing it with environmentally benign Sn. Overall, in situ reduction of oxide nanoparticles created a high-performance anode interface, further enabling large-scale applications of liquid metal anodes with solid-state electrolytes.