China Powder Network News At present, the consumption of graphite is shifting from traditional industries to strategic emerging industries. As a new type of functional material, expanded graphite has many excellent properties such as low density, light weight, high and low temperature resistance, non-toxic and harmless, environmental protection and energy saving. It is recognized as one of the most valuable and promising products in carbon materials. one. In the future, with the continuous optimization and upgrading of the industrial structure in traditional application fields and the vigorous development of strategic emerging industries such as energy conservation and environmental protection, new energy, high-end equipment manufacturing, and new materials, the consumption of the expanded graphite industry will continue to increase, with broad prospects.
for environmental protection
The interior of expanded graphite is dominated by large pores, which creates conditions for multi-molecular layer adsorption and even coagulation in the pores. It can be used to adsorb macromolecular organic matter in wastewater, and the effect is better than other adsorption materials such as activated carbon dominated by small pores. Therefore, It is often used in the treatment of oil or organic non-polar wastewater, and is an ideal material for environmental remediation of oil spills and chemical spills. Expanded graphite can be used not only for liquid phase adsorption, but also for adsorption of harmful gases in the environment.
for high-energy batteries
With the development of new energy vehicles, the world's demand for high-energy batteries 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 extremely fast charging and high cycle charging rate characteristics. Among them, expanded graphite plays a vital role. The fuel cell bipolar plate made of expanded graphite can separate the reactant gas and introduce the reactant gas into the fuel cell at the same time. In addition, expanded graphite composites can also be used as an alternative material for lithium-ion battery anodes.
For electricity storage (capacitor) field
MASIKHWA and other studies have shown that activated carbon or molybdenum disulfide/GF/expanded graphite (AEG) composites have good cycle stability as anode and cathode, respectively, and can maintain a constant 95 percent capacitance after 2000 charge-discharge cycles. It is a potential high-performance electricity storage material.
For flame retardant sealing
As a non-toxic and non-polluting flame retardant, expanded graphite can be used in combination with other flame retardant materials to significantly improve the stability and flame retardant effect of the flame retardant. Expanded graphite can significantly improve the thermal stability and flame retardant properties of materials such as polypropylene (PP) and cyclotriphosphazene (HPHPCP). It is isolated from the air and quickly extinguished. At the same time, the expanded carbon layer is tightly wrapped on the surface of the sample, which plays a good role in heat insulation, oxygen insulation and flame retardant. In addition, the acid radicals between the expanded graphite layers are released during expansion, which promotes the carbonization of the protected material. Studies have shown that acidified expanded graphite has better flame retardant effect and tensile properties.
For energy storage (wave absorption) field
Using the expanded graphite-based ring as the unit structure, BORAH et al. prepared the expanded graphite composite absorber on the flexible linear low-density polyethylene substrate, which showed extremely strong absorption in the X-band, and the absorbing performance was much stronger than the traditional Copper composite materials, and expanded graphite composite materials have the advantages of ultra-thinness, flexibility, and non-oxidation.
For other energy storage fields
In addition to the fields of wave absorption and flame retardancy, expanded graphite has also been used to prepare composite phase change materials, showing excellent energy storage properties. WU et al. invented a new method for preparing expanded graphite (EG)/stearic acid (SA) composite phase change material (CPCM) by impregnating the liquid composite phase change material (PCM) into the expanded graphite matrix, and developed an advanced The 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, excellent overall thermal performance, and the thermal conductivity is 130 times that of conventional materials.
for refractory
BEHERA et al. used expanded graphite to replace the graphite and carbon black in the Al2O3-C refractory slide, and the cold and hot strength and oxidation resistance of the new refractory prepared were significantly enhanced, indicating that expanded graphite can strengthen and improve the refractory properties of the material by absorbing and storing thermal energy. sex.
for the nuclear industry
The research of TYUPINA et al. showed that thermally expandable graphite (TEG) can improve the mechanical properties of cement compounds used for the solidification of radioactive waste oil. The waste oil was solidified at a mass ratio of 1:20, which significantly improved the solidification effect of radioactive waste oil produced by the nuclear industry. Currently, thermally expanded graphite is one of the very few minerals that has been used to cure radioactive materials to the desired effect.
for the medical field
Based on the fact that expanded graphite has strong adsorption capacity for organic and biological macromolecules, expanded graphite has a wide range of application prospects in biomedical materials. In animal experiments using expanded graphite to replace medical dressings (medical gauze), it has been shown that expanded graphite dressings have no toxic and side effects such as no blackening and irritation to the wound surface, and can promote wound healing. The relevant results of clinical trials conducted in four hospitals including the First Military Medical University Nanfang Hospital also show that the effect of expanded graphite dressing is better than that of traditional gauze drainage, and it has obvious anti-infection, antibacterial and anti-inflammatory effects.
for military use
The expanded graphite composite smoke screen agent uses the heat generated by the explosion of the pyrotechnic powder to expand, and disperses in the predetermined airspace to form an expanded graphite-type aerosol interference cloud, and then forms a certain interference in the range of visible light to millimeter wave. In modern warfare, the application of mechanization and automation improves combat efficiency and shortens the response time of combat departments.
Epilogue
With the continuous improvement of science and technology and scientific research, expanded graphite and expanded graphite composite materials are continuously used in strategic emerging fields. According to forecasts, the market is expected to reach 312 million by the end of 2025. In this regard, the preparation method of expanded graphite should be continuously improved, and more efficient, low-consumption and environmentally friendly preparation methods and modification methods at normal temperature and pressure should be explored, so as to better realize the large-scale industrial production of expanded graphite with high efficiency, environmental protection and low energy consumption. Further broaden its application scope and field.
References:
Gao Zhiyong et al. Research progress on the preparation and application of expanded graphite
Li Yan et al. Research progress on the preparation of expanded graphite by chemical oxidation
Chen Wenliang et al. Research progress and application review of expanded graphite materials
Sun Hongjuan et al. Mineralogical properties, functionalization of graphite and application of new graphite materials
Gu Qingjun. Research on the structure, properties and application of expanded graphite matrix composite phase change materials
Yang Luo et al. Research progress on the preparation and application of expanded graphite
(Edited by China Powder Network / Black Gold)
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