Graphene composites: introduction and market status - Page 41

Saab, a global company that provides world-leading products, services and solutions from military defense to civil security, is looking at applying Graphene in signature management primarily known as detection avoidance. Graphene, in combination with other natural substances, could be used to actively change the shape and topology of all manner of surfaces, including ships, aircrafts and even military uniforms.

Scientists from the UK, including ones from Manchester University, used graphene to develop a material that could convert an engine heat into electrical energy to help keep a car running (instead of going to waste) and reduce the need for fuels. It could also have applications in aerospace, manufacturing and other sectors.

Compounds that are able to capture waste heat from engines and other power systems and turn it into electricity are usually heavy, costly, toxic or only operate at high temperatures. The scientists in this study took a material called strontium titanium dioxide and added a small amount of graphene. The resulting composite was able to capture and convert heat into electric current efficiently over a broad temperature range.

The Polish graphene producer Advanced Graphene products (AGP) and Lodz University of Technology have launched a joint project to produce flexible graphene components for yachts. They plan to develop a technology that will rely on fibre-graphene components that will allow to reduce the weight of various elements while preserving, and even increasing their strength and elasticity.

The plan is for AGP to make yacht components from high strength metallurgical graphene, an enforced material patented by the Polish company. It is a graphene produced on a thin layer of metal that can easily be processed and transferred to other surfaces.

A recent IDTechEx research predicts that the graphene market will reach nearly $200 million by 2026, with the estimation that the largest sectors will be composites, energy applications and graphene coatings.

Graphene inks are said to be constantly improving (while their prices seem to be dropping), which might promote, among others, applications like sensor electrodes and smart packaging. In the transparent conductive film industry, however, it is estimated that graphene will not be able to compete with ITO films.

Researchers at VIT University, India demonstrated the application of conjugated polymer/Graphene oxide nanocomposite for thermistor applications. The study resulted in a thermistor that boasted excellent performance, suitable for electronics and sensors. A thermistor is a type of resistor whose resistance is dependent on temperature, more so than in standard resistors.

Interestingly, the study showed that lower amounts of graphene oxide (0.5, 1%) loading exhibited positive temperature coefficient, and higher loading (1.5, 2%) yielded negative temperature coefficient.

Samsung researchers reportedly developed materials that can be used to double the capacity of Li-ion batteries. The key to the more efficient batteries is a new graphene-based cathode material. It is a new silicon cathode material "coded with high-crystalline graphene". As deployed in its lithium-ion batteries the new cathodes produce cells "with twice as much capacity as ordinary lithium-ion batteries," according to various reports.

This research presents a dramatic improvement of the capacity of lithium-ion batteries by applying a new synthesis method of high-crystalline graphene to a high-capacity silicon cathode. Samsung's team used silicon cathodes instead of graphite ones; this is not a novel approach, since many previous studies have also used it. The challenge, however, is that the silicon can expand or contract during the battery charging and discharging cycles. Samsung addressed this issue by creating a process to grow graphene cells directly on the silicon in layers that can adjust to allow for the silicon's expansion: "The graphene layers anchored onto the silicon surface accommodate the volume expansion of silicon via a sliding process between adjacent graphene layers. When paired with a commercial lithium cobalt oxide cathode, the silicon carbide-free graphene coating allows the full cell to reach volumetric energy densities of 972 and 700 Wh l-1 at first and 200th cycle, respectively, 1.8 and 1.5 times higher than those of current commercial lithium-ion batteries."

Researchers at the Harbin Institute of Technology in China and the University of Michigan in the US demonstrated improved LFP battery cathode, augmented by reduced graphene oxide. The scientists used reduced graphene oxide (rGO) in LFP battery cathodes to create a new high surface area 3D composite.

LFP (or LiFePO4) is a kind of Li-Ion rechargeable battery for high power applications, such as electric vehicls, Power Tools and more. LFP cells feature high discharging current, non explosive nature and long cycle life, but its energy density is lower than normal Li-Ion cell. In this study, the researchers created the composite using a nickel foam template that was coated with layers of graphene oxide. The graphene oxide reduced as the LFP nanoparticles were synthesized in a simple technique that allows larger amounts of the LFP to be loaded into the carbon material.

Researchers at the US Department of Energy's Oak Ridge National Laboratory (ORNL) came up with an innovative large-scale graphene fabrication method. The scientists used CVD to create 2-inch-by-2-inch sheets of graphene, contained in a polymer composite. Layering graphene between polymer sheets is meant to facilitate use in commercial products, according to the scientists.

Common approaches to polymer composite fabrication use graphene flakes, creating flake dispersion and agglomeration problems. This method, however, uses graphene sheets that eliminate these problems and allow for better electrical conductivity with a lower graphene content in the composite. In fact, the scientists claim that they were able to make a nanocomposite laminate that is electrically conductive with graphene loading that is 50 times less compared to other samples.

Researchers from the VIT University in India managed to synthesize and characterize unique graphene oxide reinforced composites (prepared by colloidal blending), with potential for benefiting applications like electronics with desired dielectric properties, such as embedded capacitors. The composite's excellent stability and anti-corrosive properties make it suitable for marine and naval applications.

The composite, referred to as PEDOT-TMA/PMMA/GO, were examined by various means, namely UVVis spectroscopy, X-ray diffraction, thermogravimetric analysis, Fourier transforms infrared spectroscopy, FT-Raman spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy. It was demonstrated that the GO was homogeneously dispersed in the polymer matrix. An increase in surface roughness as a function of GO loading was also found, as well as a significant improvement in the thermal stability of composites. The composites show high values of dielectric constant and low values of dielectric loss.

EPL Composite Solutions, a subsidiary of Haydale, announced the  development of an in-house testing facility to measure and demonstrate the durability of a new generation of graphene enhanced composite gas pipes and pipeline materials. The testing facility is meant to help the company accelerate the long term testing of thermoplastic composite pipes, as well as enabling it to fast track new materials such as graphene enhanced thermoplastics into the composite pipelines.

EPL has been working closely with the oil and gas industry on the development of a process to manufacture spoolable, high pressure, fiber reinforced thermoplastic composite pipes on a continuous basis. This product is planned to become a replacement for corrosion resistant steel pipes currently in widespread use. EPL is also working closely with Haydale to incorporate graphene into the thermoplastic composite pipes in order to enhance the oil and gas permeation resistance of these materials as well as increasing the materials' long term durability.