By Akanksha Urade, Ph.D. Scholar at IIT Roorkee and Graphene & 2D Materials Science Writer
To fully realize the potential of graphene to transform numerous industries, widespread availability of defect-free graphene flakes for mass production must be achieved. Most companies today only produce low quality graphene or even graphite micro-platelets, which are of inferior quality compared to large, thin and nearly defect free (LTDF) graphene. This is the most significant factor holding back what many call the Graphene Age.
In accordance with ISO standards, there is currently no commercially available graphene production anywhere in the world that can synthesize LTDF graphene flakes, which industry needs to make existing high tech/high value products better and to introduce a whole new generation of products. Avadain has demonstrated and is scaling up to mass prodction a revolutionary, scalable and environmentally friendly manufacturing process to produce large (average app 55-100 µm2), thin (avg < 1 nm), and nearly defect-free graphene flakes in industrial quantities. Avadain believes that there are hundreds of practical applications that could benefit from high-quality graphene flakes but are currently unavailable due to the virtual absence of LTDF graphene flakes.
This article aims to shed more light on some of these potential applications:
- Electric Vehicles
Lithium-ion batteries (LIBs) are an essential element of our modern society, and they are quickly becoming the preferred battery for electric vehicles (EVs). It is mainly composed of lithium metal oxide as a cathode and lithium-graphite composite as an anode. However, there are safety concerns with these sorts of batteries due to dendrite growth on the metal electrodes during the charging process. These dendrites extend until they penetrate the separator, triggering a short circuit and, possibly, an explosion or fire in the battery. To suppress dendrites, it is critical to create new hosts for the lithium metal anode, and one such material is high-quality graphene. In a study published on the front cover of Advanced Energy Materials, researchers from China’s Sichuan University reported that in a comparative evaluation of defect free graphene and reduced graphene oxide (rGO), the defect free graphene did not enable dendritic growth whereas the rGO did. The researchers concluded that graphene defects are catalysts for dendrite development. These defects in the graphene host erode the electrolyte, resulting in the early development of dendrites. From this, it can be concluded that defect free graphene will reduce or eliminate dendritic growth in LIBs.
- Healthcare Industry
Graphene is one of the most promising new materials for biosensors, drug delivery and implantable devices like dental implants and pacemakers. However, with the market availability of a variety of “black powder” labeled “graphene”, the toxicity, health/environmental impact and biocompatibility of graphene has been at the forefront of debate. A study by scientists from the National University of Singapore firmly established that it is an impurity in graphene-like materials that causes toxicity and not graphene in of itself. Graphene produced without the use of harmful chemicals has biocompatibility, high conductivity and flexibility, making it a perfect material for use in various biomedical applications.
- Construction and Building Materials
GO is increasingly employed as an additive to improve the performance of cement and concrete due to its dispersible nature. GO material, however, has significant limitations that may limit its effectiveness in cementitious composites. It is less crystalline, has a high degree of defects and has significantly poorer mechanical properties than LTDF graphene. As a result, the use of LTDF graphene flakes in cement composites is projected to increase their structural properties. For example, researchers from the University of Adelaide revealed that LTDF graphene flakes (>55 µm) improves the strength of cementitious composite, beginning at 7 days, with a minimal dosage of merely 0.07%. The improvement accounts for an increase in cement hydration degrees as well as a decrease in distances between cement particles due to the defect-free and ultra-large size of pristine graphene.
- Flexible Electronics and Touch Screens
The rare Earth material indium tin oxide (ITO) is the industry gold standard for transparent electrodes in solar cells, touch screens and displays due to its strong optical transmission (85%) and low sheet resistance (15 Ω/sq). ITO, however, cannot be used for flexible applications since it is mechanically rigid. LTDF graphene flakes have the potential to revolutionize the landscape of flexible and transparent electrical devices. According to a University of Exeter study, chemically functionalized pristine graphene surpasses ITO due to its low resistivity of 8.8 Ω/sq, high optical transparency (absorbing a mere 2.3% of visible light) and, most significantly, flexibility. LTDF graphene flakes are critical because, for example, the resistance of reduced graphene oxide (rGO) films ranged from 1 k to 70 k Ω /sq (for 80% transmittance), which is significantly higher than ITO and so cannot be considered a feasible alternative for flexible electronics. These characteristics make LTDF graphene flakes a viable and appealing substitute for ITO.
- Water Treatment and Purification
Adsorption filters made from activated carbon or GO are widely used in modern water purification systems because of their high surface area. The issue with these filters is that they are not reusable and pose an environmental concern when discarded. Perhaps more importantly, a National University of Singapore study indicated that GO itself may impart toxins as a residual from its manufacturing process. Thus, while GO can act as a filter material it can also introduce a new hazard to drinking water. Defect free graphene has demonstrated high adsorption efficiency and electrical conductivity, outperforming traditional activated carbon and/or GO-based filters. Additionally, high-quality graphene makes water filters electrically conductive, allowing for repeated use of the filter by passing an electric current through the adsorbent material to remove adsorb contaminants like dyes, salts, bacteria and other impurities.
- Aerospace and Defense
Ultrathin, high-strength, lightweight and flexible EMI shielding materials with high shielding effectiveness are particularly desirable for numerous applications, such as aircraft, drones and spacecraft. The key criteria determining electromagnetic interference (EMI) shielding materials are high electrical conductivity, corrosion resistance and low density. Hence, LTDF graphene has enormous potential in the aerospace sector. Because of its exceptional qualities, LTDF graphene composites can be employed for ballistic protection, reducing the weight of protective armor and creating lightweight, comfortable, and protective helmets.
- Anticorrosive Coatings
Metal corrosion is a persistence and substantial global issue that costs US industries more than $200 billion each year. Graphene is also the thinnest known coating for shielding metals from corrosion. It was discovered that LTDF graphene covering on copper, nickel or most other surfaces increases corrosion resistance by 20 times. Because LTDF graphene is impermeable, the coatings act as an excellent barrier against water, oxygen and other corrosive elements.
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