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Functional Materials for Energy

Superionic cathode enables high-energy lithium-sulfur batteries


Cycling performance at a rate of C/10 for an all-solid-state Li-S battery with an LPSP sulfur cathode, demonstrating its long lifespan.

A family of new lithium polysulfidophosphate (LPSP) compounds is shown to enable stable cycling of all-solid-state lithium-sulfur (Li-S) batteries with long lifespans.  Li-S batteries have a high theoretical energy density of 2600 Wh/kg, which is about 5 times higher than that of the state-of-the-art lithium-ion batteries. Conventional Li-S batteries use liquid electrolytes, which lead to an intrinsically short lifespan of the batteries because of the loss of dissolved sulfur through the polysulfide shuttle phenomenon. The use of a solid electrolyte can efficiently prevent the polysulfide shuttle, thus achieving longevity of battery cycle-life. However, previous all-solid-state Li-S batteries have been difficult to cycle because of their sulfur cathode’s poor ionic conductivity. This research introduces the first family of sulfur-rich materials for the sulfur cathode that has a superionic conductivity for Li‑ions. The excellent cyclability demonstrated in this research is attributed to the high ionic conductivity of LPSP, which is 107 times higher than Li2S, the most conductive species in conventional sulfur cathodes. 

Z. Lin, Z. Liu, W. Fu, N. J Dudney, and C. Liang, “Lithium Polysulfidophosphates: A Family of Lithium-Conducting Sulfur-Rich Compounds for Lithium-Sulfur Batteries,” Angewandte Chemie-International Edition, DOI: 10.1002/anie.201300680.

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