Researchers from the Bourns College of Engineering at the University of California, Riverside have developed a paper-like silicon material for lithium-ion batteries, offering the potential to improve specific energy by several times for each unit weight a battery has.
In a study published in the journal Nature Scientific Reports, researchers detailed a paper-like material over 100 times thinner compared to a human hair. Led by Mihri Ozkan, a computer and electrical engineering professor, and Cengiz Ozkan, a mechanical engineering professor, the researchers produced the nanofiber material using electrospinning.
A technique that applies between 20,000 and 40,000 volts of power between a nozzle emitting a solution made up of mainly tetraethyl orthosilicate, a chemical compound commonly used by the semiconductor industry, and a rotating drum, electrospinning yielded a fiber structure made of silicon that looks very much like a sponge.
Conventionally produced anodes for lithium-ion batteries are manufactured with copper foil covered in a mixture made up of a conductive additive, polymer binder and graphite. Unfortunately, graphite has started to falter in its performance so researchers are turning to other materials to replace it.
Silicon is a good replacement candidate because it has almost 10 times the electrical charge graphite has for every battery unit weight. However, it easily degrades a battery due to dramatic volume expansion.
The new material produced in the study addresses this problem in silicon, allowing a battery to be utilized for hundreds of cycles without suffering from extensive degradation.
Zachary Favors, a UC Riverside graduate student and one of the authors of the study, explained that switching to a material that's energy-dense while taking away the need for inactive polymer binders and metallic current collectors will lead to a dramatic boost in the range abilities of an electric vehicle, for instance.
Additionally, scalability in free-standing electrodes was also tackled by the study, allowing materials like silicon nanowires or carbon nanotubes to be produced at several grams at a time.
Future work involving this kind of research will expand into integrating paper-like nanofibers into lithium-ion batteries in pouch-cell form, a larger-scale format installed in portable electronics and electronic vehicles.
The study received support from Temiz Energy Technologies. For the researchers' resulting work, the Office of Technology Commercialization at UC Riverside has moved forward to file patents.
Other authors for the study include: Rachel Ye, Hamed Hosseini Bay, Robert Ionescu, Zafer Mutlu and Kazi Ahmed. Ye, Bay, Ionescu, Mutlu and Ahmed are also graduate students from UC Riverside.
