Researchers from University of Pittsburgh discovered that the performance of lithium-ion batteries and super capacitors made from graphite and graphene is affected by their exposure to water. The study published last week in Nature Materials shows that opposite to common beliefs graphite and graphene have hydrophilic properties.
The idea for the research came as a former undergraduate engineering student, Rebecca McGinley, came across inconsistencies in the abilities of the material to react with water. Studying the phenomenon more closely, the scientists established that air contaminates the thin layer of hydrocarbon.
By using infrared spectroscopy and X-ray photoelectron spectroscopy, the team was able to determine the hydrophobic nature of the surface. However, once the contaminated layer was removed using heat, the scientists were able to observe that the materials became hydrophilic.
According to the authors, the reason for this is the emission of hydrocarbon into the air by plastics and other types of materials. This is the first time a scientific team looks into possible contamination on the surface of the materials, mainly because the process of contamination is very fast and it has most likely occurred on all samples used until now.
The wettability is the driving factor behind energy storage capabilities of devices made of graphite and graphene. Establishing this property of the materials could lead to the development of much more durable lithium-ion batteries and more efficient super capacitors.
The next challenge in front of the team is to look more closely into their findings and establish the exact impact this property has on various applications of graphite.