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my country started late in the field of heat conduction. As high-end product technology is still monopolized by a few companies in Europe, America and Japan, many domestic thermal interface material manufacturers still mainly export low-end products, and their sales account for only about 10% of the total market. Traditional mobile phone heat dissipation materials are mainly TIM materials (thermally conductive interface materials) such as graphite sheets and thermally conductive gels. At present, heat pipes and VC (soaking plates) have begun to penetrate from the fields of computers and servers to smart phone terminals, and graphene materials have also begun to be applied. In contrast, VC and graphene have high thermal conductivity and low thickness, and are better heat dissipation materials.
The mainstream heat dissipation material, the consumption of a single mobile phone is 3~6 pieces. Graphite is a better thermally conductive material than metals such as copper and aluminum. The main reason is that graphite has a special hexagonal planar network structure, which can evenly distribute heat on a two-dimensional plane and effectively transfer it. In the horizontal direction, the thermal conductivity of graphite is 300~1900W/(m*K), while the thermal conductivity of copper and aluminum is about 200~400W/(m*K). In the vertical direction, the thermal conductivity of graphite is only 5-20W/(m*K). Therefore, graphite has good horizontal thermal conductivity and vertical thermal resistance. At the same time, the specific heat capacity of graphite is equivalent to that of aluminum, about twice that of copper, which means that after absorbing the same amount of heat, the temperature of graphite will rise only half of that of copper. In addition, the density of graphite is only 0.7~2.1g/cm3, which is much lower than 8.96g/cm3 of copper and 2.7g/cm3 of aluminum, so it can be lightweight and can smoothly adhere to any flat and curved surfaces.
Based on the performance advantages of high thermal conductivity, high specific heat capacity and low density, graphite has been used in consumer electronics in batches since 2009, and has been widely used in smart phones in 2011. It has now replaced traditional metals and has become the mainstream heat dissipation material in the consumer electronics field. .
01 The highest thermal conductivity, good electrical conductivity, and huge space for downstream lithium battery materials and thermal conductive films
Graphene is the substance with the highest known thermal conductivity, with a theoretical thermal conductivity of 5300W/(m*K), which is much higher than graphite. It is a honeycomb-shaped two-dimensional crystal formed by a single layer of carbon atoms hybridized by electron orbitals, with a thickness of only 0.335nm. It is also called single-layer graphite, which is an allotrope of carbon nanotubes and fullerenes. According to the China Graphene Industry Technology Innovation Strategic Alliance Standard, single-layer graphene refers to a two-dimensional carbon material composed of a layer of carbon atoms.
Graphene's rapid thermal conductivity and rapid heat dissipation characteristics make it an ideal alternative to traditional graphite heat dissipation films, which are widely used in smart phones, tablet computers, high-power energy-saving LED lighting, ultra-thin LCD TVs and other heat dissipation. In addition to high thermal conductivity, graphene has other excellent physical and chemical properties, so it has a wide range of downstream applications. For example, it has high conductivity and can be used in the fields of integrated circuits, conductive agents, sensors and lithium batteries; high specific power, can be used as super capacitors and energy storage components; strong flexibility, bending does not affect performance, and can be used as a flexible material for curved surfaces Screens and wearable devices; with high light transmittance, it can be used for transparent conductive films.
Application areas of graphene films include:
(1) Thermally conductive film, used for the heat dissipation layer of smart phones and tablet computers;
(2) Flexible display, used in fields such as flexible display screens and wearable devices;
(3) Sensor materials, used in wearable devices, medical and environmental monitoring and other fields;
(4) Basic materials for integrated circuits, used in fields such as supercomputers, high-frequency chips, and precision electronic components.
Research on graphene began to appear in 1994. In 2004, British scientists Andre Heim and Konstantin Novoselov successfully separated graphene, which was awarded the Nobel Prize in Physics in 2010. In recent years, graphene research has continued to gain popularity, the number of patents has continued to increase, and the process of industrialization has also continued to advance.
The theoretical research and industrialization of graphene in my country rank among the top in the world. In terms of theoretical research, according to the data of the Graphene Industry Alliance, as of 2016, in the statistics of major priority patent applications in the world, my country's graphene patents accounted for 58% (followed by South Korea and the United States); in terms of industrialization, graphene is in Occupying a key position in the strategic frontier materials, China plans to achieve the development goal of the graphene industry to "form an industry scale of tens of billions by 2020, and the overall industrial scale to exceed 100 billion by 2025".
