Researchers at the University of California, Riverside (UCR) have created and tested a silicon-tin nanocomposite anode that they say will improve the charge capacity and stability of lithium-ion batteries, which are often used in consumer electronics.

Rechargeable lithium-ion batteries are composed of three main parts: an anode, a cathode and a lithium salt dissolved in an organic solvent. While graphite is the material of choice for most anodes, its performance is a limiting factor in making better batteries and expanding their applications.

Both silicon and tin have been investigated as novel high-performance alternatives for graphite anodes. Researchers led by Lorenzo Mangolini, associate professor of mechanical engineering and materials science and engineering in UCR’s Bourns College of Engineering, have now shown that combining both materials into a single composite can lead to dramatic improvements in battery performance.

The silicon-tin nanocomposite viewed by high-angle annular dark field imaging. The larger green particles are silicon and the smaller red particles are tin. Image credit: University of California, Riverside.Mangolini says adding tin to the silicon, rather than another conductive material such as carbon black, circumvents the low conductivity of silicon without decreasing energy storage. The result can be achieved with the addition of even minor amounts of tin—as little as 2% by weight—he adds.

“The synergistic effects between these two materials lead to batteries that exceed the performance of each of the two components alone, an improvement that is a result of the high electrical conductivity and good energy storage capacity of tin," Mangolini says.

In addition to tripling the charge capacity offered by graphite, the silicon-tin nanocomposite is extremely stable over many charge-discharge cycles, essentially extending its useful life, he says. These features, coupled with a simple manufacturing process, could help the expansion of lithium-ion batteries for use in next-generation vehicles.

“Lithium-ion batteries are growing in popularity for electric vehicles and aerospace applications, but there is a clear need to alleviate range anxiety—the fear that a vehicle won’t have enough charge to reach its destination—before we will see large-scale adoption," Mangolini says.

UCR's Office of Technology Commercialization has filed a patent application on this research.