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US scientists use self-healing technology to create longer-lasting battery 18650 rechargeable

Researchers at the University of Illinois (UI) have found a way to apply self-healing technology to lithium-ion batteries, which is expected to create reliable and longer-lasting batteries.

The researchers developed a new battery that uses a silicon nanoparticle composite material on the negative side of the battery and combines the composite material in a novel way - an inherent problem with silicon-containing batteries.

Nancy Sottos, professor of materials science and engineering at the University of Illinois, and Scott White, professor of special engineering, led the research team to conduct this research and published a related research report in the journal Advanced Energy Materials.

Nancy Sottos, professor of materials science and engineering at the University of Illinois, and Scott White, professor of special engineering, led the research team to develop a silicon nanoparticle composite material that can be used for battery anodes, which is expected to be used to create more reliable and long-lasting batteries.

"This work is fairly new to the field of self-healing materials because it applies to materials that store energy," White said. "It's a completely different type of goal. In addition to restoring structural properties, you also have the ability to heal the stored energy."

Inside lithium-ion batteries that power portable devices or electric vehicles, the negatively charged electrode, or anode, is typically made from a composite of graphite particles. These batteries work well, but take a long time to charge, and over time, they don't hold a charge as long as they did when they were new.

"Silicon has a very high capacity, and with that high capacity you get more energy out of the battery, but it also goes through a lot of expansion due to the cycling of the battery and its self-pulverization," Sottos said.

Previous studies have found that battery anodes made from nano-sized silicon particles are less likely to break down, but have other problems.

"The battery keeps charging and discharging, one, two, three times, and eventually it loses capacity because the silicon particles start to break away from the binder," White said.

To address this problem, the team took the silicon anode a step further by giving it the ability to repair itself. The self-healing occurs through reversible chemical bonds that connect the silicon nanoparticles to the polymer binder.

"This dynamic rebonding process basically holds the silicon particles and the polymer binder together, which greatly improves the long-term performance of the electrode," Sottos said.

The researchers tested the new battery without reversible chemical bonding and found that it retained 80% of its initial capacity even after 400 charging cycles.

The batteries also had a higher energy density, meaning they could store more power than a graphite-anode battery of the same size.

"The higher the energy density, the better. Another option is to add more cells, but that also adds a lot of weight, especially for electric vehicles," Sottos said.

Future research will include studying how this self-healing technology works with solid-state batteries, the researchers said. Recent incidents of lithium-ion battery fluids igniting and even exploding are urging scientists to look in this direction.

The research program was sponsored by the Center for Electrochemical Energy Science, an advanced energy research center funded by the U.S. Department of Energy's (DoE) Office of Science, Basic Energy Sciences.

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