Scientists have been searching for a way to make batteries hold longer charges, on both a commercial and industrial scale. South Korean researchers have made headway in this development, creating a form of 3D graphene “pom-poms” that have a much more efficient energy capacitance than normal graphene.
Graphene can be used as a supercapacitor due to its stability, high conductivity, and large surface area. 3D graphene capacitors are even better because their greater surface area enhances their capacitance. Graphene capacitors are relatively simple, with a carbon-only structure, and versatile enough to incorporate into batteries as electrodes. However, current ways of manufacturing graphene electrodes yield thin films that may stack and aggregate, which decreases surface area and makes the resulting material more difficult to process. These issues have led to the development of graphene foams and aerogels, but these can’t be used as electrodes because they’re too irregular and not as carbon-dense. Thus, scientists are currently looking to develop ways to create 3D carbon nanostructures for potential use as battery electrodes. Continue reading →
With the availability of cost effective and easily scalable synthesis methods, researchers have begun working with porous and 3D graphene and carbon nanotube (CNT) structures. Wang, Sun, and Chen (2014) wrote a review article outline uses for foam-like structures of CNTs, graphene, and hybrids of the two. Using a process called chemical vapor deposition, it is possible to construct defect free 3D architectures. This type of method is currently used in thin film production, i.e. production of semiconductor wafers in photovoltaic cells. Continue reading →
Bernardi et al. (2013) investigated the absorbance of graphene and three different monolayer transition metal dichalcogenides (TMDs)—MoS2, MoSe2, and WS2—alone and in various combinations as the active layer in ultrathin photovoltaic (PV) devices. In calculating the upper limits of the electrical current density (measured in mA/cm2), each material can contribute to the total absorption of a device. The authors found that subnanometer thick graphene and TMD monolayers can absorb the equivalent short-circuit currents of 2–4.25 mA/cm2, while 1 nm thick Si, GaAs, and P3HT (commonly used materials in current PV devices) were found to generate currents between 0.1–0.3 mA/cm2. Further testing suggested that the high absorption of the monolayer MoS2 is due Continue reading →