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⋅m−1⋅K−1 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⋅m−1⋅K1 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.

Latest Graphene Thermal Conductivity news

Northwestern team develops multi-functional graphene oxide hair dye

Researchers from Northwestern University have developed a hair dye based on graphene oxide that "does not include toxic compounds commonly used in hair dyes". As an added bonus, graphene-colored hair enjoys much less electrostatic frizz. Due to graphene’s thermal conductivity, the dye may even help dissipate heat on hot days. The team has filed a provisional patent for the color.

Northwestern team develops GO hair dye image

The researchers "used the biopolymer chitosan and ascorbic acid (vitamin C) to disperse flakes of graphene oxide (GO)—and the darker derivative, reduced GO—in water," which reportedly formed a smooth coating on the hair surface.

U.S-based startup develops a graphene-based seat warming technology for cars

A U.S-based startup called Promethient Inc. has developed a new graphene-enhanced seat warmer technology that it says is more efficient and durable than similar available systems. The company has developed the Thermavance conductive heat transfer system, which uses conduction of heat as opposed to most of the other technologies that rely on transfer of heat through convection for the purpose of warming seats.

In the common case of convective seats, seats have to be perforated so that the air can be moved through the seating surface. This makes the surface of the seats more prone to damage from wear-and-tear and from water. In the Thermavance heat transfer system, however, Promethient uses a solid-state thermoelectric module and graphene in order to transfer heat directly to the occupant of the seat instead of first either heating or cooling the surrounding air.

Graphene Investment Guide

Graphene 3D Lab to use graphene to harvest thermal energy produced in Bitcoin mining

Graphene 3D Labs logoGraphene 3D Lab patents a graphene-based technology to harvest thermal energy produced in Bitcoin mining. The supercomputers used to mine Bitcoin and other digital currencies give off a lot of thermal energy, which is currently mostly wasted, and so G3L's technology will be used to capture this energy and redirect it to power fridges and A/C units.

Graphene 3D Lab’s technology uses graphene-based modules to harvest the thermal energy given off by these powerful machines and redirects it into heating and/ or refrigeration solutions. Not only will G3L’s technology boost return on investment for data center operations, it is also expected to help reduce the environmental footprint of data processing.

Graphene-based heating devices hit the market

Several companies in China are now commercializing graphene-based heating elements, embedded in wearable and other devices. Many such devices are now available, shipping globally via retailers such as Amazon and others.

BriGenius Graphene Far-Infrared electric heating pad photo

Graphene is an excellent thermal conductor, and using it for heating devices is somewhat surprising. The producers of these devices explain that graphene is strong, thin and flexible, and it provides "pure far infrared radiation" and is also safer and moreenvironmentally friendly compared to other alternatives. Whether this is actually so is an open question.

XG Sciences to expand with new graphene production facility

XG Sciences, a US-based developer and producer of graphene flakes, has announced its plan to invest millions in expanding its Lansing-area facilities. The company will start operating out of new 64,000 square-foot facility in Vevay Township in March.

XG Sciences' new plant image

The company was formed in 2006 based on work out of Michigan State University. The company's technology can be used in automotive batteries and as wire coatings in electronics to prevent microchips from overheating. Some of the material has been used in Samsung phones as a thermally conductive adhesive, said current CEO Philip Rose. Rose also said the expansion marks the first phase in a move toward larger scale commercialization for the company.

Versarien - Think you know graphene? Think again!Versarien - Think you know graphene? Think again!