Healable cathode may unlock potential of solid-state lithium-sulfur batteries

The work was revealed within the journal Nature on March 6.

Strong-state lithium-sulfur batteries are a kind of rechargeable battery consisting of a stable electrolyte, an anode fabricated from lithium metallic and a cathode fabricated from sulfur. These batteries maintain promise as a superior various to present lithium-ion batteries as they provide elevated vitality density and decrease prices. They’ve the potential to retailer as much as twice as a lot vitality per kilogram as standard lithium-ion batteries — in different phrases, they may double the vary of electrical automobiles with out growing the battery pack’s weight. Moreover, using plentiful, simply sourced supplies makes them an economically viable and environmentally friendlier selection.

Nonetheless, the event of lithium-sulfur solid-state batteries has been traditionally tormented by the inherent traits of sulfur cathodes. Not solely is sulfur a poor electron conductor, however sulfur cathodes additionally expertise important enlargement and contraction throughout charging and discharging, resulting in structural harm and decreased contact with the stable electrolyte. These points collectively diminish the cathode’s skill to switch cost, compromising the general efficiency and longevity of the solid-state battery.

To beat these challenges, a group led by researchers on the UC San Diego Sustainable Energy and Power Heart developed a brand new cathode materials: a crystal composed of sulfur and iodine. By inserting iodine molecules into the crystalline sulfur construction, the researchers drastically elevated the cathode materials’s electrical conductivity by 11 orders of magnitude, making it 100 billion occasions extra conductive than crystals fabricated from sulfur alone.

“We’re very excited in regards to the discovery of this new materials,” mentioned examine co-senior creator Ping Liu, a professor of nanoengineering and director of the Sustainable Energy and Power Heart at UC San Diego. “The drastic enhance in electrical conductivity in sulfur is a shock and scientifically very attention-grabbing.”

Furthermore, the brand new crystal materials possesses a low melting level of 65 levels Celsius (149 levels Fahrenheit), which is decrease than the temperature of a scorching mug of espresso. Which means the cathode may be simply re-melted after the battery is charged to restore the broken interfaces from biking. This is a vital function to deal with the cumulative harm that happens on the solid-solid interface between the cathode and electrolyte throughout repeated charging and discharging.

“This sulfur-iodide cathode presents a singular idea for managing a number of the important impediments to commercialization of Li-S batteries,” mentioned examine co-senior creator Shyue Ping Ong, a professor of nanoengineering on the UC San Diego Jacobs Faculty of Engineering. “Iodine disrupts the intermolecular bonds holding sulfur molecules collectively by simply the correct amount to decrease its melting level to the Goldilocks zone — above room temperature but low sufficient for the cathode to be periodically re-healed by way of melting.”

“The low melting level of our new cathode materials makes repairing the interfaces attainable, an extended sought-after resolution for these batteries,” mentioned examine co-first creator Jianbin Zhou, a former nanoengineering postdoctoral researcher from Liu’s analysis group. “This new materials is an enabling resolution for future excessive vitality density solid-state batteries.”

To validate the effectiveness of the brand new cathode materials, the researchers constructed a take a look at battery and subjected it to repeated cost and discharge cycles. The battery remained secure for over 400 cycles whereas retaining 87 % of its capability.

“This discovery has the potential to resolve one of many largest challenges to the introduction of solid-state lithium-sulfur batteries by dramatically growing the helpful lifetime of a battery,” mentioned examine co-author Christopher Brooks, chief scientist at Honda Analysis Institute USA, Inc. “The flexibility for a battery to self-heal just by elevating the temperature may considerably prolong the whole battery life cycle, creating a possible pathway towards real-world utility of solid-state batteries.”

The group is working to additional advance the solid-state lithium-sulfur battery expertise by bettering cell engineering designs and scaling up the cell format.

“Whereas a lot stays to be finished to ship a viable stable state battery, our work is a major step,” mentioned Liu. “This work was made attainable due to nice collaborations between our groups at UC San Diego and our analysis companions at nationwide labs, academia and business.”

This work was supported partly by the U.S. Division of Power (DOE) Superior Analysis Initiatives Company-Power (DE-AR0000781), the U.S. DOE Workplace of Science (DEAC02-05-CH11231).

Disclosures: Ping Liu and Jianbin Zhou report a U.S. provisional patent utility filed on February 13, 2023, Serial No. _63/484,659, based mostly on this work.