Graphene is the material with the highest known thermal conductivity, and its theoretical thermal conductivity reaches 5300W / m〃K, which is much higher than graphite. It is a honeycomb-shaped two-dimensional crystal formed by the hybridization of a single layer of carbon atoms through electron orbits. The thickness is only 0.335nm. It is also called a single layer of graphite. It is an allotrope of carbon nanotubes and fullerenes. According to the standard of China's graphene industry technology innovation strategic alliance, single-layer graphene refers to a two-dimensional carbon material composed of a layer of carbon atoms. Graphene's fast thermal conductivity and rapid heat dissipation characteristics make it an ideal alternative material for traditional graphite heat dissipation films, and is widely used in heat dissipation for smartphones, tablet computers, high-power energy-saving LED lighting, and ultra-thin LCD TVs. In addition to high thermal conductivity, graphene has other excellent physical and chemical properties, so it is widely used downstream. For example, high conductivity, can be used in 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, can be used as a flexible material for curved surfaces Screen and wearable devices; with high light transmittance, can be used for transparent conductive film.
Graphene product forms include film and powder, and the application fields of graphene powder include: (1) conductive additives for positive and negative materials of lithium batteries, which can improve charge and discharge speed and cycle performance; (2) supercapacitor electrodes Materials, with strong energy storage activity and excellent cycle performance; (3) Feature coatings, doped in anti-corrosion coatings, heat dissipation coatings and conductive coatings as additives to improve coating performance; (4) High-efficiency catalysts, used in the field of energy and chemical industry The application fields of graphene film include: (1) thermal conductive film, used for heat dissipation layer of smart phones and tablet computers; (2) flexible display, used for 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 supercomputers, high-frequency chips and precision electronic components.
Lithium battery materials and thermal conductive films are expected to become the largest downstream applications. In the Mate 20 X smartphone released by Huawei in 2019, graphene was used as a heat dissipation material for the first time. Graphene lithium batteries are also expected to be commercialized on mobile phones. From the perspective of market scale, according to the estimation of the China Merchants Industry Research Institute, the market space for lithium battery materials is the largest, which is expected to reach 4 billion to 5 billion yuan, followed by thermally conductive films, which is expected to reach 1.5 to 2 billion yuan. It is also around 2 billion yuan.
According to the statistics of China Graphene Industry Alliance, the scale of my country's graphene industry has increased from 16.3 million US dollars in 2015 to 38.42 million US dollars in 2016. With the resolution of the mass production of graphene and the expansion of the downstream, it is expected that my country's graphene market will reach USD 200 million in 2020, surpassing 50% of the global market and becoming the largest graphene consumer country.
3.2. my country's graphene industry is a global leader with many participants
Graphene related research began to appear in 1994. In 2004, British scientists Andre Heim and Konstantin Novoselov successfully separated graphene and won the 2010 Nobel Prize in Physics. In recent years, graphene research has continued to gain momentum, the number of patents has continued to increase, and the process of industrialization has also continued to advance.
my country's graphene theoretical research and industrialization are among the highest in the world. In terms of theoretical research, according to the graphene industry alliance data, as of 2016, in the world's main priority patent application statistics, China's graphene patents accounted for 58% (secondly South Korea and the United States); industrialization, graphene in Strategically leading materials occupy a key position. China plans to achieve the graphene industry's development goal of "forming a tens of billions of industrial scale in 2020 and breaking the scale of the entire industry by 2025".
According to statistics from the China Graphene Industry Alliance, Chinese graphene production enterprises have grown from more than 300 in 2015 to more than 400 in 2016. In terms of graphene thermal film, CZFX graphene technology company is the technology leader and first commercialized in smartphones. The company's graphene thermal film has been widely used in Huawei mate 20 series, P30 series and other terminal products.
There are many preparation methods, and the development prospect of CVD method is good
The upstream of graphene includes graphite and other resources, equipment and systems. The downstream applications include thermal conductivity, electrical conductivity, flexible display screens and ink coatings. There are two product forms of graphene powder and graphene film.
Graphene powder and graphene film have significant differences in preparation methods. In general, the preparation methods of graphene include physical method, chemical method and biological method. Among them, the physical method mainly includes mechanical peeling method, liquid phase peeling method and vapor phase peeling method; chemical method includes redox method, vapor deposition method (CVD) and SiC epitaxial growth method; biological method includes redox method. Graphene powder is mainly prepared by mechanical peeling method, liquid phase peeling method, gas phase peeling method and redox method, and graphene film is mainly prepared by mechanical peeling method, vapor deposition method (CVD) and epitaxial growth method. From the perspective of technology maturity and large-scale mass production, under the redox method, the number of layers of graphene powder is the smallest, and the process flow is relatively simple; the size of the graphene film under the CVD method is the largest, so it has become a relatively industrial and development prospect Good two directions.