Researchers have developed a new battery that uses a silicon nanoparticle composite material on the negative side and combines the composite material together in a novel way—a problem inherent in silicon-containing batteries.
The research team, led by Nancy Sottos, Professor of Materials Science and Engineering, and Scott White, Professor of Special Engineering, at the University of Illinois, conducted this study and published their findings in the journal Advanced Energy Materials.
A research team led by Nancy Sottos, a professor of materials science and engineering, and Scott White, a professor of special engineering, at the University of Illinois, has developed a silicon nanoparticle composite material that can be used as a battery anode, which is expected to be used to create more reliable and long-lasting batteries.
“This research is quite new for the study of self-healing materials because it can be applied to materials that store energy,” White said. “It’s a completely different type of target. In addition to restoring structural properties, it also has the ability to heal stored energy.”
Inside lithium-ion batteries used to power portable devices or electric vehicles, the negatively charged electrodes or anodes are typically made of a composite material of graphite particles. These batteries perform well, but they take a long time to charge, and over time, the charging time becomes less than when the battery was new.
Sottos said, "Silicon has a fairly high capacity, and such a high capacity allows you to get more energy from the battery. However, due to the battery cycle and its self-pulverization, it also undergoes a lot of expansion."
Previous research has found that battery anodes made of nanoscale silicon particles are unlikely to decompose, but rather present other problems.
White said, "The battery is continuously charged and discharged, going through one, two, three times until the final capacity loss, because the silicon particles begin to detach from the binder."
To address this problem, the research team further refined the silicon anode by endowing it with self-healing capabilities. This self-healing phenomenon occurs through reversible chemical bonding between the silicon nanoparticles and the polymer binder.
“This dynamic rebonding process essentially keeps the silicon particles and polymer binder together, significantly improving the long-term performance of the electrode,” Sottos said.
Researchers tested a new battery that did not use reversible chemical bonding and found that it retained 80% of its initial capacity even after 400 charge cycles.
These batteries also have higher energy density, meaning they store more electricity than graphite-anode batteries of the same size.
“The higher the energy density, the better. Another option is to add more batteries, but that also adds a lot of weight, especially since electric vehicles are facing this problem,” Sottos said.
Researchers say future studies will include exploring how this self-healing technology can be integrated with solid-state batteries. Recent incidents of spontaneous combustion and even explosions caused by liquid in lithium-ion batteries are prompting scientists to pursue this research direction.
This research program was sponsored by the Center for Electrochemical Energy Science, an advanced energy research center funded by the Office of Science and Basic Energy Sciences of the U.S. Department of Energy (DoE).
