Scientists put the ​"solve" in ​"solvent" for lithium-sulfur battery challenge

phys.org | 9/30/2019 | Staff
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Lithium-ion batteries represent the majority of batteries in consumer electronics and electric vehicles. Today, scientists are looking for new chemistries that could improve the energy density and performance of batteries beyond conventional lithium-ion batteries.

One type of these batteries, called lithium-sulfur batteries, could offer more energy density and lower cost than the traditional graphite/metal oxide lithium-ion battery. However, its performance is frequently impaired by a parasitic reaction that happens inside the battery that prevents it from cycling as efficiently.

Study - Scientists - US - Department - Energy

Now, in a new study, scientists at the U.S. Department of Energy's Argonne National Laboratory have discovered how a certain class of electrolyte material can reduce the frequency of this reaction, potentially paving the way for more effective lithium-sulfur batteries.

When a lithium-sulfur battery is charged, an unavoidable side reaction called lithium polysulfide shuttling frequently occurs. As the battery charges, lithium sulfide is converted to sulfur on the cathode, but some lithium-sulfur compounds that are incompletely oxidized can dissolve from the cathode into the electrolyte—the liquid region of the battery that separates the two electrodes.

Point - Compounds - Anode - Cathode - Process

At this point, the lithium-sulfur compounds can diffuse and become reduced on the anode and oxidize back on the cathode. This process can go over and over again in a way that wastes the battery's charge without putting it to work.

"With the polysulfide shuttle, you're getting nothing out of your battery except for heating it up," said Argonne chemist Chi Cheung Su, an author of the study. "In electrochemical terms, it's like trying to fly from New York to Los Angeles, but getting stuck traveling back and forth between Chicago and Denver."

Part - Reason - Initiation - Polysulfides - Happens

A large part of the reason for the initiation of the polysulfides shuttling happens because the polysulfides are able to dissolve readily...
(Excerpt) Read more at: phys.org
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