Recently, the project "Professional Preparation and Application of High-Quality Graphene Thermal Film" by Professor Lu Hongbin from the Department of Polymer Science of Fudan University was unveiled at the 7th China (Shanghai) International Technology Import and Export Fair.
Since its discovery in 2004, as the thinnest and highest strength material to date, graphene has attracted widespread attention from researchers worldwide. For more than a decade, Lu Hongbin's team has made a series of breakthrough progress in the innovative development and industrial application of graphene and its composites. The water phase stripping method proposed by the team to quickly and efficiently prepare high-quality graphene has solved the high cost and process of graphene. Key issues such as tediousness, difficult storage and transportation, etc. The proposed new technologies for the preparation of various composite materials such as ultra-large layers of graphene oxide, controllable number of layers of high-quality graphene, ultra-clean graphene, and spontaneous stripping of graphene have solved the scale of graphene Core issues in business applications. The graphite heat-dissipating film presented at the Shanghai Fair is a new graphene material newly developed by Lu Hongbin's team, which is expected to replace the existing high-cost, high-energy-consumption products.
Preparation of high-quality graphene thermal film is expected to improve the thermal management efficiency of portable electronic devices
Graphene has very good application prospects in thermal film products. Graphite thermal film is a thermally conductive thin film material with controlled thickness and excellent overall performance. It can be widely used in thermal management of various devices such as smart phones, notebook computers, and communication base stations. With the continuous development of 5G communication equipment and LED equipment, the growth space of the thermal film market is getting wider and wider.
Polyimide pyrolytic artificial graphite film is a widely used heat dissipation film product on the market. The key technology for the preparation of its raw material polyimide film (PI film) is in the hands of foreign companies, and there is fierce competition in the middle and lower reaches of the Chinese market. Due to the lack of core technologies in raw materials, product prices continue to fall, and corporate profitability continues to be squeezed.
The graphene heat dissipation film developed by Lu Hongbin's team uses natural flake graphite as the raw material. The cost is low, the thickness of the material is controllable in the range of 2-20 microns, the thermal conductivity is high, the flexibility is good, and it can be continuously bent for more than 20,000 times. No attenuation. The prepared heat-dissipating film is pasted on an electric heating sheet, and the temperature can be reduced by 40 ° C. Graphene heat dissipation film has low cost, high cost performance, simple and efficient process, and is expected to replace artificial graphite film in a comprehensive manner. It will also provide new heat dissipation solutions for wearable devices, flexible displays, and high-power weapons and equipment.
Lu Hongbin said, "The preparation of high-quality graphene heat-dissipating film starts from natural graphite, not only has little environmental pollution, but also has outstanding cost performance, or will subvert the existing technology." This breakthrough in core technology is expected to drive many downstream products to achieve Complete localization.
Continuously break through the core technology of graphene preparation
As early as 2008, Lu Hongbin's team noticed the fascinating properties of graphene. "Graphene has very good electrical and thermal conductivity, and there is no satisfactory solution to improve the electrical and thermal conductivity of polymer materials." Combining the two together, using graphene to modify polymer materials And given it more functionality, it became the original intention of Lu Hongbin's team to explore the graphene field for ten years. He frankly stated, "Only by mastering the source technology can we effectively promote the innovation and development of related technologies."
Soon, Lu Hongbin's team prepared the technical combination of polymer materials and graphene in the laboratory. After this basic technical problem was solved, the team began to explore the feasibility of industrialization of graphene in 2010, but they found that due to the nature of graphene, it is greatly affected by various factors such as its structure, size, holes and defects. At that time, it was very difficult to obtain graphene on the market that met production requirements.
Taking into account the needs of future industrial production, it would be very advantageous to use water as a solvent to achieve large-scale production of graphene. However, graphite and graphene are both hydrophobic substances. Due to the large specific surface area, graphene will float on the water surface and graphite will sink to the bottom. It is not easy to make hydrophobic graphite peel off into graphene in water.
After three years of repeated experiments, the team proposed a unique technology that can strip millions of layers of graphene together into a single layer of high-quality graphene, which not only achieves efficient stripping of graphene, And the process is simple and efficient, and easy to industrialize. This laid a solid foundation for the mass production and application of graphene.
After achieving breakthroughs in key technologies, Lu Hongbin was faced with the problems of application and industrialization of related technologies, which prompted him to consider how to extend graphene research downstream.
Water phase stripping technology makes mass production of graphene with smaller sheets possible, but how to control the molecular weight of graphene and prepare graphene sheets with different sizes is still a key issue to be solved. Previously, people used large-scale graphene to prepare graphene through hierarchical screening. The process was complicated, and it was difficult to mass-produce mass-produced graphene. The prepared graphene had an uneven lattice structure and was far from practical applications for mass production. Lu Hongbin's team took a different approach and adopted a new route to retain the graphene sheet in the raw graphite to the maximum extent. This is the earliest technology for the preparation of ultra-large graphene oxide.
Lu Hongbin's team also proposed a low-cost technology for intercalation at room temperature, thousand-fold expansion, and defect-free graphene. In the future, graphene three-dimensional structures prepared by room temperature chemical expansion will become key basic raw materials in applications such as composite materials, energy storage materials, and environmental governance. The team changed the traditional method of preparing graphene by high temperature expansion, and adopted a chemical expansion method at room temperature and pressure to expand graphite into a three-dimensional graphene structure with a large specific surface area. The latter has better properties than traditional high temperature expansion graphite. The pore structure, electrical and thermal conductivity, and lattice integrity of the product have extremely broad prospects in the fields of environmental protection, energy storage, and composite materials. In particular, the unique technology proposed by the team for the spontaneous exfoliation of graphite in polymer materials to achieve graphene, and achieve uniform dispersion and retention of the lattice structure, is expected to provide ideals for the functional compounding and large-scale production of polymers and graphene Industrialization approach.
In Lu Hongbin's view, the team's research on graphene is a highly relevant process. "From the control of graphene's molecular size, to the three-dimensional structure of graphene molecules, to the breakthrough in the application of graphene spontaneous peeling and recombination, this is a highly relevant whole. We will ultimately make graphene's preparation process and downstream applications The industrialization process is organically integrated. "
"Graphene is an area where big stories can be told"
Lu Hongbin clearly realized that although China's graphene industrialization technology has taken the lead in the world, there is still a long way to go before people can truly feel the great advantages of graphene. "Graphene has very good application potential. In some key areas, we have completed prospective research accumulation, including small-scale experiments close to industrialization. Related technological breakthroughs have already formed a certain impact at home and abroad. It can be said that This is the key foundation for pushing graphene products into practical applications. "Lu Hongbin said," The industrialization of graphene has entered a critical period. Continuous efforts will eventually release the potential of graphene in various fields and form irreplaceable. Applications. "
In fact, some graphene has been applied in some fields. Graphene obtained from water phase peeling can greatly increase the charging speed of lithium-ion batteries, which may provide a new solution for the "mileage anxiety" of electric vehicles. In addition, graphene can also be put into practical use as a functional additive for polymer materials, which can not only impart excellent electrical and thermal properties to the material, but also change its processability. Lu Hongbin takes the application of graphene as a rheology modifier as an example. "Graphene is a two-dimensional substance with a large anisotropy ratio, which can significantly change the flow behavior of fluids. Parts and thin film processing are very important. "In addition, Lu Hongbin is also optimistic about the application prospects of graphene as a sensor. He pointed out that we can now use the excellent performance of graphene to monitor many physiological indicators and physical conditions of newborns and patients with severe illness.
At present, the technologies such as graphene aqueous phase stripping technology and mass production of graphene three-dimensional structure proposed by Lu Hongbin's team have been patented. The new method proposed by the team for the controllable modification of polymer chains on the surface of graphene has been widely cited by domestic and foreign counterparts. Many industrial parks threw olive branches at them and hoped that the relevant projects could be implemented as soon as possible.
"Graphene is an area that can tell big stories. How to highlight the advantages of Shanghai and Fudan is also an important question for me at this stage." Lu Hongbin said, "In my opinion, the so-called basic research is to continue Make more original results, and promote social progress through the transformation of results. Ultimately, industrialization must be our direction. "