1.5v Alkaline battery.Research on the application of graphene-based absorbing materials

　　With the development of electronic information technology and the popularization of electronic products, electromagnetic waves widely exist in people's daily lives. When electromagnetic radiation exceeds the upper limit that the human body and the environment can bear, electromagnetic pollution will occur. In the field of special operations, special forces are still a common means of searching for targets in modern warfare. The development of special stealth materials that can efficiently absorb electromagnetic waves is one of the effective ways to improve the survivability of weapon systems. Therefore, absorbing materials have extensive research value and application prospects in civil and special fields. Graphene is a new two-dimensional nanomaterial first discovered in 2004. Its magical two-dimensional structure gives it unique physical and chemical properties. Graphene is the most conductive material currently known. The speed of electrons in graphene can reach 1/300 of the speed of light. The valence band and conduction band of graphene intersect at the Fermi level, which gives graphene unique zero-gap semiconductor properties that are twice as high as the current highest mobility indium antimonide material. In the future, graphene may replace silicon in manufacturing ultra-miniature transistors, increasing the computing speed of computer processors by a hundred times. The strength of graphene is equivalent to more than 100 times that of the best steel, and its hardness even exceeds that of diamond. It is currently the strongest material in nature, but its density is very small. At room temperature, the thermal conductivity of graphene is more than ten times that of commonly used metal thermal conductive materials such as gold, silver, and copper, and more than twenty times that of aluminum. Graphene also has some other special properties, such as ultra-high specific surface area. The theoretical specific surface area of single-atomic layer graphene can reach an astonishing 2630m2/g, which is 2 to 3 times the specific surface area of activated carbon. It can be used to adsorb and desorb various large molecules and small particles. The optical transmittance of graphene reaches 97.7%. This characteristic gives graphene the potential to be used as transparent electrodes in solar cells. The above characteristics make it possible for graphene to replace traditional carbon materials and become a new type of electromagnetic wave absorbing material. However, it is unavoidable that, similar to other carbon materials, the main electromagnetic wave attenuation mechanism of simple graphene is electrical loss, so its wave absorption performance is insufficient. good. Compounding carbon materials with ferrite and electrically lossy metal compound nanoparticles is an effective way to improve the wave absorption performance. Graphene has a large specific surface area and is very suitable as a carrier to load nanoparticles. It can not only effectively solve the problems of poor dispersion of nanoparticles and easy aggregation of themselves, but also design and optimize its structure and performance at the nanoscale, thereby preparing nanoparticles with Graphene-based multifunctional composite absorbing materials with specific composition, structure and properties. 1. Graphene’s wave absorption mechanism When electromagnetic waves encounter any shape of medium during propagation, reflection and transmission will occur at the incident surface or interface of the electromagnetic waves. Since the wave impedance of the original propagation medium does not match the wave impedance of the material, part of the electromagnetic wave will be reflected, while the other part will be transmitted into the medium. The greater the impedance mismatch, the more electromagnetic waves are reflected. Only when the wave impedance of the original propagation medium matches that of the material will the electromagnetic wave be incident into the material with maximum efficiency. During the propagation process within the material, electromagnetic waves interact with the material and are converted into other forms of energy (such as mechanical energy, electrical energy, thermal energy, etc.), that is, electromagnetic wave loss. Therefore, the absorbing performance of absorbing materials is mainly determined by two conditions: one is the impedance matching characteristics, that is, reducing the reflection of electromagnetic waves on the surface of the material or maximizing the penetration of electromagnetic waves into the interior of the material; the other is the attenuation characteristics, that is, the electromagnetic waves entering into the material Once inside the material, the material can effectively absorb or lose electromagnetic waves and reduce secondary reflection of electromagnetic waves. Multi-component graphene-based absorbing materials use composite hybrid particle microstructure and synergistic effects, and study the loading density, morphology, structure, component content of each component and the synergistic effect between each component of the absorbing material. The influence of electromagnetic parameters, while using the special structure of graphene and the special properties brought about by the composite of graphene and nanoparticles, such as interface polarization, electron relaxation polarization and dipole polarization to lose electromagnetic waves, and obtain It has developed a lightweight, high-strength, broadband absorbing material structure system with multiple electromagnetic wave loss mechanisms and adjustable performance. 2. Research status and inspiration of graphene absorbing materials In recent years, researchers have done a lot of valuable work on graphene absorbing materials. The design and preparation of multi-component system graphene-based composite absorbing materials and research on electromagnetic wave absorption properties have just been carried out internationally. Characteristics such as high specific surface area, excellent electrical properties and special two-dimensional structure all endow graphene with excellent potential as an ideal building block of new composite absorbing materials. However, the comprehensive absorbing performance of graphene-based composite absorbing materials remains to be seen. improve. The use of nanoparticles of multiple components to composite with graphene reduces the agglomeration of graphene sheets to a certain extent. More importantly, the prepared multi-component composite materials have multi-functions. For absorbing materials, each The materials of the components have different electromagnetic wave absorption properties. When the materials of multiple components are combined, the absorbing material can take into account the advantages of that material and achieve complementary advantages. However, there are also obvious shortcomings in the preparation of multi-component composite materials. For example, the compatibility of different interfaces is poor, and the dispersion and uniformity of multi-component materials are difficult to control. Despite this, the design and preparation of multi-system graphene-based composite absorbing materials will still become the focus of future research on new absorbing materials. As a new base material, graphene will also promote the technological development of stealth materials and electromagnetic protection. Research provides greater impact

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