The Elements of Innovation Discovered
The Elements of Innovation Discovered
Metal Tech News - January 9, 2023
Sulfur is an abundant and cost-effective mineral that can hold more energy than traditional ion-based lithium batteries.
Increased energy density at lower costs is the ultimate goal when it comes to making better batteries for smartphones, toys, tools, and electric vehicles. Lithium-sulfur batteries have shown the potential to outperform traditional lithium-ion batteries on both these fronts.
This is why scientists at the U.S. Department of Energy's Argonne National Laboratory are working to overcome a pitfall that stands in the way of commercial production of these batteries that pair sulfur-containing positive electrodes (cathodes) with lithium metal negative electrodes (anodes).
Having the cathodes in these batteries made with sulfur, an extremely abundant and inexpensive element, offers cost and material supply advantages over lithium-ion batteries with cathodes made from costlier materials such as nickel and cobalt.
While lithium-sulfur batteries have the potential for significant energy density storage gains at lower costs when compared to the lithium-ion batteries currently in use, they have one detrimental setback that has prevented them from being viable – the polysulfide (sulfur species) in the battery dissolves into the electrolyte. Once dissolved, the polysulfides are "shuttled" in the electrolyte, causing corrosion that lowers the life of the battery and the number of times it can be charged.
To prevent this battery-killing problem, scientists have tried placing a protective layer between the cathode and anode. Earlier iterations of this idea were to use a redox-inactive layer that does not undergo reactions like those in an electrode as the shield. This inactive layer, however, added substantial weight to the battery without completely solving the problem that it was designed to overcome.
"Previous experiments with cells having the redox-inactive layer only suppressed the shuttling, but in doing so, they sacrificed the energy for a given cell weight because the layer added extra weight," said Guiliang Xu, an Argonne National lab chemist and co-author of the paper.
The Argonne National Lab team decided to try something a little different – a porous interlayer made from sulfur.
Tests show that lithium-sulfur batteries with this porous sulfur divider had an initial capacity roughly three times higher than those with the redox-inactive layer interlayer. Even better, the cells with the active interlayer maintained high capacity over 700 charge-discharge cycles.
Laser experiments carried out at Argonne's Advanced Photon Source confirmed that a redox-active interlayer does indeed reduce shuttling and detrimental reactions within the battery, as well as increase the battery's capacity to hold more charge and last for more cycles.
"These results demonstrate that a redox-active interlayer could have a huge impact on Li-S battery development," said Wenqian Xu, a scientist at Argonne's Advanced Photon Source. "We're one step closer to seeing this technology in our everyday lives."
Now that the concept has been proven, the Argonne scientists are focused on improving the porous sulfur interlayer for lithium-sulfur batteries.
"We want to try to make it much thinner, much lighter," Guiliang Xu said.
With more than 16 years of covering mining, Shane is renowned for his insights and and in-depth analysis of mining, mineral exploration and technology metals.
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