Researchers at the University of California have developed a new silicon paper that may replace graphite in traditional lithium-ion batteries.
The paper, made of spongy silicon nanofibers, is a good replacement candidate because its electrical charge is almost 10 times more than graphite per unit weight of the battery. The nanofibers were produced using electrospinning, whereby 20,000 to 40,000 volts are applied between a rotating drum and a nozzle, which emits a solution composed mainly of tetraethyl orthosilicate (TEOS), a chemical compound frequently used in the semiconductor industry. The nanofibers are then exposed to magnesium vapor to produce the sponge-like silicon fiber structure.
In the past, silicon has been problematic because it degrades quickly in the battery, but the silicon nanofibers allow the battery to cycle hundreds of times without degrading.
This advance is significant to the electric vehicle industry because reserves of graphite are dwindling and demand for batteries continues to increase. This technology can allow researchers to develop large scale, binderless batteries like those used in electric vehicles and portable electronics.
Researchers have discovered a way to use silicon microfibers, pictured here, to replace graphite in batteries. Credit: UC Riverside.