What is the future development prospects of graphene batteries in the field of lithium-ion batteries

by:CTECHi     2021-09-09
In today's highly developed science and technology, a variety of high-tech appears in our lives, bringing convenience to our lives, so do you know the graphene batteries that these high-tech may contain? Graphene is A planar two-dimensional nanomaterial with a hexagonal honeycomb lattice composed of carbon atoms. The length of the CC bond is 0.141nm, the theoretical density is about 0.77mg/m2, and the thickness is only the diameter of carbon atoms. Carbon atoms participate in hybridization in sp2 mode, and electrons can be smoothly conducted between the layers. Therefore, graphene has excellent electrical conductivity and is currently considered to be the material with the smallest resistivity. This is also the reason why graphene has a bright future in battery development. one. Graphene materials have excellent thermal conductivity, and the theoretical room temperature thermal conductivity of a single-layer material can reach 3000-5000W/(m*K). This attribute can be used to study heat dissipation during battery operation. It has excellent mechanical properties, is a material with excellent toughness and strength, and can be used for the development and research of flexible electrode materials. In addition, the high specific surface area and high light transmittance of graphene also have high research value. Lithium batteries are cathodes made of graphene composite nano-materials, with coated metal lithium as the negative electrode, and ceramic fiber separators are used to resist the components of the refractory electrolyte. The coated lithium flakes inhibit the growth of lithium dendrites. The fiber membrane can prevent accidental penetration of dendrites, and the fire-proof and explosion-proof electrolyte can prevent fire and explosion accidents. Based on the special physical and chemical properties of graphene, graphene has great development potential in the field of electrode material research. According to different application fields, the application of graphene materials in lithium-ion batteries can be roughly divided into three categories: the application of graphene in cathode materials, the application in anode materials, and other applications in lithium-ion batteries. Currently, graphene is added to lithium-ion batteries in three forms: conductive additives, electrode composite materials, and directly used as negative electrode materials. Among them, the conductivity and discharge performance of graphene conductive additives are far superior to traditional conductive agents. They do not involve complex synthetic processes in the preparation process, so they have strong controllability, low difficulty and high success rate. At present, graphene's research and development technology for conductive agents is relatively mature. The positive electrode is made of mechanical graphene as an important new material, and the coated metal lithium is used as the negative electrode to form a lithium-ene battery. After more than a thousand cycles, the results show that the initial specific capacity can reach up to 1800mAh/g, and it is stable at 100 times. Above 1200mAh/g, it is approximately equal to 4 to 5 times that of ordinary lithium-ion batteries. It is stable at 1100mAh/g at 200 times, 400~00 times is also stable above 1000mAh/g, to 700~800 times, all are above 900mAh/g, and at 1100 times, there is also a ratio of 700mAh/g or more The capacity is two or three times higher than that of ordinary lithium-ion batteries. Significant progress has been made in 2019. While the specific capacity is increased to more than 2700mAh/g, it is also felt that the energy of lithium ene batteries still has a lot of room for improvement. The study found that the material formed after graphene half-wrapped LiFepO4 can improve the conductivity of LiFepO4 material, but the ion transmission efficiency decreases after full wrapping, and it is speculated that it may be because lithium ions cannot pass through the six-membered ring structure of graphene. Some researchers have ultrasonically mixed LiFepO4 nanoparticles with graphite oxide to produce a LiFepO4/graphene composite with a more processed microstructure. After the material is further coated with conventional carbon, the specific capacity of lithium insertion is greatly improved, and it can still be maintained at about 70mAh/g under the condition of high rate of 60C. Although LGGFlex can self-repair minor scratches, it still cannot change the shortcomings of easily damaged phones. However, if mobile phones and other digital products can use graphene as a shell in the future, they will become rock solid. According to a report by the American Chemical Society, graphene is 200 times harder than steel, which is obviously very durable. Researchers at Columbia University say that graphene has a certain degree of ductility and can be stretched by 20%. In other words, graphene is actually a flexible material, similar to rubber. Samsung has been studying graphene transistors to produce flexible screens. In addition, graphene batteries also have a certain degree of water resistance, and are expected to be applied to a new generation of waterproof equipment. Graphene has good electrical conductivity, but its two-dimensional microstructure is easy to stack on each other, which makes the research on graphene independent electrode materials unsatisfactory. It is mainly manifested in the differential performance and low cycle efficiency of the battery. The reversible specific capacity of graphene prepared by Honma et al. In the first cycle, it can reach 540mAh/g (current density is 50mA/g), but the reversible specific capacity drops faster after multiple cycles. The above are some detailed analysis of graphene batteries that are worth learning. I hope that I can give you some help when you are just getting in touch. If you have any questions, you can also discuss it with the editor.
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