"When the battery starts discharging, the sulfur at the cathode starts losing electrons and forming sulfur tetrachloride (SCl 4), using chloride it stole from the electrolyte. As the electrons flow into the anode, they combine with the sodium, which plates onto the aluminum, forming a layer of sodium metal. Obviously, this wouldn't work with an aqueous electrolyte, given how powerfully sodium reacts with water."
"To form a working battery, the researchers separated the two electrodes using a glass fiber material. They also added a porous carbon material to the cathode to keep the sulfur tetrachloride from diffusing into the electrolyte. They used various techniques to confirm that sodium was being deposited on the aluminum and that the reaction at the cathode was occurring via sulfur dichloride intermediates."
The battery chemistry uses sulfur at the cathode that loses electrons to form sulfur tetrachloride (SCl4) by extracting chloride from the electrolyte. Electrons flowing to the anode combine with sodium, which plates onto aluminum to form a metallic sodium layer. A glass-fiber separator isolates the electrodes and a porous carbon additive in the cathode prevents SCl4 diffusion into the electrolyte. Diagnostic techniques confirmed sodium deposition on aluminum and cathode reactions proceeding via sulfur dichloride intermediates. Sodium dichloride proved a poor sodium-ion source because it precipitates onto solid components. The cell survived about 1,400 cycles with faster capacity decay at higher charge rates and retained over 95% charge after 400 days idle. Projected electrode-level energy density can exceed 2,000 Wh/kg, with raw-material cost estimated near $5 per kWh.
Read at Ars Technica
Unable to calculate read time
Collection
[
|
...
]