What are Graphene Cooling Materials? What are Their Uses?
Overview: As electronic devices and products evolve towards higher integration and computational power, the power consumption increases exponentially, making heat dissipation a pressing issue. So, what are graphene cooling materials, and what are their uses?
As electronic devices and products evolve towards higher integration and computational power, the power consumption increases exponentially, making heat dissipation a pressing issue. So, what are graphene cooling materials, and what are their uses?
1. About Thermal Conductivity
Traditional thermal conductive materials primarily include metals (silver, copper, aluminum, etc.), metal oxides (Fe2O3, BeO, Al2O3, etc.), and other non-metallic materials (graphite, carbon black, AlN, etc.).
Historically, traditional cooling materials like copper and aluminum have been used in the heat dissipation field for electronic devices and products. Recently, graphene cooling materials have emerged as a new type of cooling material. They are considered highly competitive due to their excellent thermal conductivity, rapid heat dissipation (through air convection), light weight, and good flexibility.
2. Principle of Graphene Cooling Materials
Graphene cooling materials are two-dimensional carbon nanomaterials composed of carbon atoms arranged in a hexagonal honeycomb lattice with SP hybrid orbitals.
Graphene cooling materials exhibit excellent optical, electrical, and mechanical properties, making them highly promising in fields such as information science, micro-nano processing, energy, biomedicine, and drug delivery. They are considered future reactive materials.
Graphene cooling materials are among the strongest known materials while also possessing good flexibility and the ability to bend. Graphene’s theoretical Young’s modulus is 1.0 TPa, and its intrinsic tensile strength is 130 GPa. Modified graphene cooling materials using hydrogen plasma also exhibit excellent strength, with a uniform modulus reaching up to 0.25 TPa. Graphene paper composed of graphene sheets has many pores, making it brittle. However, functionalized graphene obtained through oxidation, when made into graphene paper, becomes solid and tough.
Graphene cooling materials have outstanding thermal conductivity. Pure, defect-free single-layer graphene has a thermal conductivity as high as 5300 W/mK, which is the highest known for carbon materials, surpassing single-walled carbon nanotubes (3500 W/mK) and multi-walled carbon nanotubes (3000 W/mK). When used as a carrier, its thermal conductivity can reach 600 W/mK. Additionally, the ballistic thermal conductivity of graphene can lower the ballistic thermal conductivity limit per unit circumference and length of carbon nanotubes.
Graphene cooling materials also have excellent optical properties, with an absorption rate of about 2.3% over a wide wavelength range, making them almost transparent. In the range of several graphene layers’ thickness, the absorption rate increases by 2.3% for each layer of graphene thickness.
Large-area graphene cooling materials exhibit excellent optical performance, which varies with the thickness of the graphene. This is due to the unusual low-energy electronic structure of single-layer graphene. By applying voltage to a dual-gate double-layer graphene field-effect transistor at room temperature, the bandgap of graphene can be adjusted between 0 and 0.25 eV. When a magnetic field is applied, the optical response of graphene nanoribbons can be tuned to the terahertz range. Thermodynamically, the heat dissipation of graphene cooling films in graphite radiators includes methods such as conduction, convection, and radiation.