Graphite keeps 'expanding' in strategic emerging fields

At present, the consumption of graphite is shifting from traditional industry to strategic emerging industry.  As a new functional material, expanded graphite has many excellent properties, such as low density, light weight, high and low temperature resistance, non-toxic, harmless, environmental protection and energy saving, etc. It is recognized as one of the products with the most use value and application prospect in carbon materials.  In the future, with the continuous optimization and upgrading of the industrial structure in the traditional application fields and the great efforts to develop strategic emerging industries such as energy conservation and environmental protection, new energy, high-end equipment manufacturing and new materials, the consumption of expanded graphite industry will continue to increase and the prospect will be broad.  

Used in the field of environmental protection  

Expanded graphite internal is given priority to with big hole, multiple molecular layer adsorption and coagulation in hole created the conditions, macromolecular organic matter in waste water can be used for adsorption, which is mainly composed of holes is better than activated carbon or other adsorption materials, therefore, often used in oil or non-polar organic waste water treatment, oil leakage and chemicals leakage accident environment ideal material of repair.  Expanded graphite can be used not only for liquid phase adsorption, but also for adsorption of harmful gases in the environment.  

Used in the field of high energy batteries  

With the development of new energy vehicles, the demand for high-energy batteries in the world is increasing, and the application of expanded graphite in the field of high-energy batteries is becoming more and more extensive, especially in the research of super batteries with the characteristics of ultra-fast charging and high cycle charging rate, expanded graphite plays a crucial role.  The fuel cell bipolar plate prepared with expanded graphite can separate the reaction gas and transfer the reaction gas into the fuel cell at the same time.  In addition, expanded graphite composites can also be used as a substitute material for the anode of lithium ion batteries.  

Used in electric storage (capacitor) field  

MASIKHWA et al. showed that activated carbon or molybdenum disulfide /GF/ expanded graphite (AEG) composite materials used as the negative and positive supercapacitors respectively had good cycle stability and could still maintain a constant 95% capacitance after 2000 charge-discharge cycles, which was a potential high-performance electric storage material.  

Used in flame retardant sealing field  

As a non-toxic and pollution-free flame retardant, expanded graphite can be used in combination with other flame retardant materials to significantly improve the stability and flame retardant effect of flame retardant.  Expanded graphite can significantly improve the thermal stability and flame retardant performance of polypropylene (PP) and cyclotriphosphazene (HPHPCP) and other materials, PP/EG and HPHPCP/EG composites will generate an expanded carbon layer after combustion, so that the flame is isolated from air, quickly extinguished, while the expanded carbon layer tightly coated on the surface of the sample.  Play a very good heat insulation, oxygen insulation, flame retardant role.  In addition, the acid roots between the expanded graphite layers are released during the expansion, which promotes the carbonization of the protected material.  The results show that the acidified expanded graphite has better flame retardancy and tensile properties.  

For energy storage (wave absorption) field  

BORAH by expanded graphite base circle as the unit structure, flexible in linear low density polyethylene substrate was prepared by expanded graphite composite absorber, of x-band showed strong absorbent, absorbing performance is far better than the traditional copper composite material, and the expanded graphite composite material has the advantages of thin, flexible, non oxidation.  

For other energy storage fields  

In addition to absorbing and flame retardant fields, expanded graphite is also used to prepare composite phase change materials, showing excellent energy storage performance.  By impregnating liquid composite phase change material (PCM) into expanded graphite matrix, WU et al. invented a new method for preparing expanded graphite (EG)/stearic acid (SA) composite phase change material (CPCM), and developed an advanced stable modular energy storage unit.  The results show that the expanded graphite/stearic acid composite phase change material has stable morphology, obvious anisotropic thermal conductivity and excellent overall thermal properties, and the thermal conductivity is 130 times that of the conventional material.  

Used in refractory field  

BEHERA et al. used expanded graphite to replace graphite and carbon black in al2o3-C refractory plate, and the cold and thermal strength and oxidation resistance of the new refractory material were significantly enhanced, indicating that expanded graphite can strengthen and improve the fire resistance of the material by absorbing and storing heat energy.  

Used in the nuclear industry  

TYUPINA et al. 's study showed that thermal expanded graphite (TEG) could improve the mechanical properties of cement compounds used for the solidification of radioactive waste oil, and solidified the waste oil at a mass ratio of 1∶20, significantly improving the solidification effect of radioactive waste oil produced in the nuclear industry.  At present, thermally expanded graphite is one of the few minerals used to cure radiation to the desired effect.  

Used of medicine

Due to its strong adsorption capacity for organic and biological macromolecules, expanded graphite has a wide application prospect in biomedical materials.  The animal experiment of using expanded graphite to replace medical dressing (medical gauze) shows that expanded graphite dressing has no black, no stimulation and other toxic and side effects on wound surface, and can promote wound healing.  The results of clinical trials conducted in four hospitals including Nanfang Hospital of The First Military Medical University also showed that the effect of expanded graphite dressing was better than that of traditional gauze in drainage, and had obvious anti-infection, antibacterial and anti-inflammatory effects.  

Used in the military field  

The expanded graphite composite smokescreen makes use of the heat expansion generated when pyrofireworks explode and disperses in the predetermined airspace to form the expanded graphite aerosol interference cloud, and then forms certain interference in the range of visible light to millimeter wave.  In modern warfare, the application of mechanization and automation has improved operational efficiency and shortened the response time of operational departments.