Researchers have been taking different approaches to applying self-healing technology—mainly in the form of materials that can autonomously repair small cracks or tears—to develop longer-lasting and more durable electronic devices.

Some of the latest research in this area comes out of the University of Illinois, where researchers have developed a lithium-ion battery that applies a self-healing technology to improve the battery’s performance. 1

However, the approach is slightly different than previous ones, according to lead researchers and University of Illinois professors Nancy Sottos and Scott White, in that it applies not to the structure of materials, but to the battery’s ability to store energy.

“It’s a different type of objective altogether,” said White, an aerospace engineering professor. “Instead of recovering structural performance, we’re healing the ability to store energy.”

The self-healing capability is based in differences at the chemical level, Materials Science and Engineering Professor Sottos explained to Design News in an interview.

“Prior reports of silicon-microparticle-composite electrodes with a self-healing polymer are based on reversible-hydrogen bonding,” she said. “The polymer is fused to the silicon microparticles and keeps them in electrical contact as they pulverize. The resulting electrode has a significant amount of polymer mass and relatively low active material content.”

Sottos and White’s work, on the other hand, is based on the development of silicon-composite electrodes with dynamic ionic bonding to increase cycle lifetimes and reliability as lithium-ion battery anodes through the restoration of interfaces between active silicon nanoparticles and the binder, she said.

“The self-healing takes at the interface between the particle and the binder, enabling a much higher amount of active material,” Sottos said.

The researchers and their team published a paper about their work in the journal Advanced Energy Materials.

Professors Scott White and Nancy Sottos from the University of Illinois have developed a lithium-ion battery that applies self-healing technology to improve performance. White is professor of aerospace engineering, while Sottos is professor of materials science and engineering. (Source: University of Illinois)

Specifically, the team developed a battery that uses a silicon-nanoparticle-composite material on its negatively charged side, and a novel way to hold the composite together—repairing a typical problem with batteries that contain silicon.

The negatively charged electrode, or anode, inside the lithium-ion batteries that power devices and electric cars are typically made of a graphite particle composite. While the batteries work well, it takes a long time for them to recharge, and that charge deteriorates and does not last long over time as it does when the batteries are new.

“Silicon anodes are of great interest for lithium-ion batteries due to their very high capacity--about seven times greater than the graphite electrodes used in current laptop batteries,” Sottos said. “Use of these high-capacity materials in commercial electrodes, however, is hampered by the enormous expansion and contraction--as much as 400 percent--as lithium ions diffuse in and out during cycling, causing damage to the silicon, loss of electrical connection to the electrodes, and significant capacity fade in just a few use cycles.”

The technology the University of Illinois team developed, however—composite anodes with self-healing ionic bonding—“demonstrate a higher-capacity retention of approximately 80 percent for 400 cycles, as well as good rate capability,” she said.

“The dynamic ionic bonds effectively mitigate the degradation in capacity that occurs due to the large volume change of silicon anodes during lithium intercalation, opening up a new avenue to improve reliability and performance of lithium-ion batteries,” Sottos said.

The University of Illinois has filed a patent application for the team’s work and are hoping to take the technology out of lab and into commercialization through a startup company, she added. In the meantime, researchers are working to generalize the approach they’ve taken to other electrode materials and potentially to solid-state batteries, Sottos said.



Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 15 years. She currently resides in a village on the southwest coast of Portugal.