Graphene thermal conductivity - introduction and latest news

Graphene thermal conductivity

Thermal transport in graphene is a thriving area of research, thanks to graphene's extraordinary heat conductivity properties and its potential for use in thermal management applications.

The measured thermal conductivity of graphene is in the range 3000 - 5000 W/mK at room temperature, an exceptional figure compared with the thermal conductivity of pyrolytic graphite of approximately 2000 W/mK  at room temperature. There are, however, other researches that estimate that this number is exaggerated, and that the in-plane thermal conductivity of graphene at room temperature is about 2000-4000 W/mK for freely suspended samples. This number is still among the highest of any known material.

Graphene is considered an excellent heat conductor, and several studies have found it to have unlimited potential for heat conduction based on the size of the sample, contradicting the law of thermal conduction (Fourier's law) in the micrometer scale. In both computer simulations and experiments, the researchers found that the larger the segment of graphene, the more heat it could transfer. Theoretically, graphene could absorb an unlimited amount of heat.

The thermal conductivity increases logarithmically, and researchers believe that this might be due to the stable bonding pattern as well as being a 2D material. As graphene is considerably more resistant to tearing than steel and is also lightweight and flexible, its conductivity could have some attractive real-world applications.

But what exactly is thermal conductivity?

Heat conduction (or thermal conduction) is the movement of heat from one object to another, that has a different temperature, through physical contact. Heat can be transferred in three ways: conduction, convection and radiation. Heat conduction is very common and can easily be found in our everyday activities - like warming a person,s hand on a hot-water bottle, and more. Heat flows from the object with the higher temperature to the colder one.

Thermal transfer takes place at the molecular level, when heat energy is absorbed by a surface and causes microscopic collisions of particles and movement of electrons within that body. In the process, they collide with each other and transfer the energy to their neighbor, a process that will go on as long as heat is being added.

The process of heat conduction mainly depends on the temperature gradient (the temperature difference between the bodies), the path length and the properties of the materials involved. Not all substances are good heat conductors - metals, for example, are considered good conductors as they quickly transfer heat, but materials like wood or paper are viewed as poor conductors of heat. Materials that are poor conductors of heat are referred to as insulators.

How can graphene,s exciting thermal conduction properties be put to use?

Some of the potential applications for graphene-enabled thermal management include electronics, which could greatly benefit from graphene's ability to dissipate heat and optimize electronic function. In micro- and nano-electronics, heat is often a limiting factor for smaller and more efficient components. Therefore, graphene and similar materials with exceptional thermal conductivity may hold an enormous potential for this kind of applications.

Graphene's heat conductivity can be used in many ways, including thermal interface materials (TIM), heat spreaders, thermal greases (thin layers usually between a heat source such as a microprocessor and a heat sink), graphene-based nanocomposites, and more.

Haydale Graphene Industries and Staircraft report progress on graphene-based underfloor heating trials

Specialist structural flooring manufacturers Staircraft have been testing the use of Haydale's graphene-based functional ink for application on their innovative chipboard flooring system. Significant investment has reportedly been made to get the new flooring system to adopt a heating solution that is cost effective and easy to install.

In a recent trial, Staircraft has reported very encouraging results and is now focused on continuing to collect definitive data before introducing the concept to their customer base. 

Read the full story Posted: Jul 13,2024

Graphene Composites USA selected to join U.S Military footwear project

Graphene Composites USA (GC) has been selected to participate in a research and development program between DEVCOM Soldier Center, Natick MA and UMass Lowell, to develop materials for the next generation of U.S. military footwear.

The program, SWIFT [Supporting Warfighters through Innovative Footwear Technologies], is offered by the HEROES (Harnessing Emerging Research Opportunities to Empower Soldiers) initiative and will see GC extend its patented GC Composite graphene and aerogel technology to develop ultra-lightweight, durable, insulative materials for use in extreme cold weather.

Read the full story Posted: Jul 05,2024

Researchers develop new approach for controlling thermal emission

Researchers from the University of Manchester, The Pennsylvania State University, Koç University and Vienna University of Technology (TU Wien) have tackled the challenge of control of thermal radiation, demonstrating a new topology-based approach.

The team explained that conventional approaches to tailoring thermal emission using metamaterials are hampered both by the limited spatial resolution of the required subwavelength material structures and by the materials’ strong absorption in the infrared. In their recent work, the scientists developed an approach based on the concept of topology: by changing a single parameter of a multilayer coating, they were able to control the reflection topology of a surface, with the critical point of zero reflection being topologically protected. 

Read the full story Posted: Jun 10,2024

Haydale demonstrates graphene ‘Hot Seat’ at the Advanced Materials Show 2024

Haydale recently displayed, for the first time in public, its revolutionary new solution to automotive seat heating labelled the ‘Hot Seat’ at the NEC in Birmingham. Using the Company's patented process and unique materials, Haydale has developed an alternative to existing automotive seat heating technology.

This interesting graphene application is based on the production of a seat heater that is faster to heat, uses less energy and offers a green and eco-friendly alternative to the current solutions. Using the same technology in place for their Underfloor Heating range of products under development, Haydale has now adapted this to provide a novel application for heated seating.

Read the full story Posted: May 26,2024

Graphene-based masterbatches: Marrying performance with ecological responsibility

GrapheneUP®, an industry vanguard in manufacturing verified few-layer graphene and a diverse array of graphene-centric intermediary products, announces the debut of MASTERGUP® — an innovative line of thermoplastic masterbatches. This breakthrough harnesses the transformative potential of graphene, setting a new benchmark for sustainability and recyclability within multiple sectors.

Graphene, distinguished by its exceptional strength and conductivity, imparts enhanced thermoplastic properties, including mechanical robustness, thermal stability, and gas barrier properties. These advancements extend the lifespan of products and significantly reduce waste, thereby contributing to more excellent environmental stewardship. Moreover, incorporating the graphene GUP® into thermoplastic matrices elevates processability, streamlining the molding, reshaping, and recycling processes. GUP®-fortified thermoplastics demonstrate remarkable endurance through repeated recycling, mitigating material degradation — a commendable achievement in material sustainability.

Read the full story Posted: Mar 27,2024

Nottingham houses test graphene-infused infrared wallpaper

A trial is underway in 45 social housing groups across the UK that could revolutionize the way we heat our homes, especially those that have long battled with issues like heat leakage and inefficient insulation. A graphene-enhanced infrared wallpaper, developed by NexGen Heating, is being tested in a project targeting social housing and older properties that are notoriously hard to insulate.

By infusing wallpaper with graphene, NexGen Heating has created a product that emits infrared heat, warming objects and people directly in a manner reminiscent of sunlight. This direct form of heating is not only efficient but also customizable to fit the aesthetics of any room, promising an unobtrusive addition to homes. Furthermore, the potential for integration with solar panels and batteries could make this a cornerstone of sustainable living, significantly reducing reliance on fossil fuels. NexGen Heating says infrared can provide greener, cheaper heating when paired with solar panels and batteries. 

Read the full story Posted: Feb 27,2024

Researchers review graphene's potential and limitations for cooling solar panels

Researchers at  Monash University Malaysia and Tunku Abdul Rahman University of Management and Technology have studied how graphene and graphene derivatives could be used as materials to reduce the operating temperature of solar panels. They reviewed the limitations and potential of solar module cooling techniques based on graphene and found that high costs and graphene treatments are the main challenges to overcome.

In a recent in-depth review, the team explained that graphene has attracted the interest of the scientific community as a medium to enhance heat transfers in cooling systems. When used for PV cooling applications, graphene can be used in different ways. For example, as a selective absorber coating or embedding it into a working fluid as a nanofluid. Graphene nanoparticles can also be added to thermal interface materials (TIMs) or phase change materials (PCMs) used for solar module cooling. 

Read the full story Posted: Feb 03,2024

Researchers develop novel graphene coating that converts waste heat into electrical energy

Researchers at the University of Sussex and the University of Brighton have presented their recent work on thermoelectric capture, using highly conductive graphene sheets, which aims to improve technologies that capture and convert heat into electricity and tackle the barriers standing before these methods. The aims to advance the possibility of cheap, sustainable technologies for heat capture and conversion – as well as reach a new understanding of how conductivity in graphene-based nanomaterials can be best exploited.

The team assembled nanomaterial networks of varying density and size, from few to many layers of graphene sheets, then measured electrical conductivity as the different arrays were exposed to heat. Their expectation was that the assemblies of larger, thicker sheets would exhibit the highest levels of conductivity but in fact, the opposite outcome was observed, where the smaller, thinner sheets spontaneously formed dense-packed arrays, and performed better than the many-layered samples. 

Read the full story Posted: Jan 11,2024

Haydale secures SMART funding to accelerate development of graphene infused heat transfer fluids

Haydale has announced the award of a SMART Flexible Innovation Support Grant ("SMART FIS") from the Welsh Government, to accelerate development of ultra-efficient, graphene infused heat transfer fluids.  This support will assist in the development and proof of concept of scientific innovations, in a commercial setting.

Hydratech, a division of Liquitherm Technologies Group and longtime manufacturer of aqueous-based heat transfer fluids, have been awarded a collaborative SMART FIS to work in partnership with Haydale on the project.

Read the full story Posted: Dec 06,2023

Purdue team claims graphene's thermal conductance properties may not be as impressive as previously thought

Purdue researchers have examined graphene's thermal properties and found they may not be as revolutionary as previously thought. 

Graphene is often touted as the world's best heat conductor, surpassing diamond - which was previously thought to be able to transfer the most heat the quickest. Diamond’s thermal conductivity is generally understood to be about 2,000 W/(m K). But when scientists started measuring graphene’s thermal conductivity, early estimates reached above 5,000 W/(m K). However, subsequent experimental measurements and modeling have refined graphene’s thermal conductivity and brought the number down to around 3,000, which is still quite better than diamond. The Purdue team focused n this graphene property and found something altogether different.

Read the full story Posted: Nov 30,2023