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American scientists study that the energy density of carbon fiber lithium air batteries can be increased by four times

according to the report of the American physicist organization, American scientists have developed a new carbon fiber lithium air battery with a wait-and-see attitude. Its energy density is four times that of rechargeable lithium-ion batteries now widely used in automobiles. This study was published in the latest issue of the journal energy and environmental science

last year, a scientific research team led by Yang Shaohong, a professor of mechanical engineering and materials science and engineering at the Massachusetts Institute of Technology (MIT), improved the energy density of lithium air batteries by using rare metal crystals. Theoretically, the energy density of lithium air battery is higher than that of lithium-ion battery, because it uses a porous carbon electrode to replace the cumbersome solid-state electrode. The carbon electrode can store energy by capturing oxygen from the air floating above it. Oxygen and lithium ions combine to form lithium oxide

the latest research takes a step forward. The carbon fiber electrode produced has more pores than other carbon electrodes. Therefore, when the battery is discharged, there are more pores to store solid lithium oxide

Robert Mitchell, the collaborator of this paper and a graduate student in the Department of materials science and engineering at MIT, said: "we have used the chemical vapor deposition process to plant vertically arranged carbon nanofiber arrays. These arrays, like blankets, are energy storage" scaffolds "with high conductivity and low density to actively do a good job in the layout of intellectual property rights in the field of new materials

another researcher, beta Galante, a graduate student in the Department of mechanical engineering at MIT, explained that during the discharge process, lithium peroxide particles will appear on carbon fibers, and carbon will increase the weight of the battery. Therefore, it is very important to minimize the amount of carbon and leave enough space for lithium peroxide, which is an active chemical formed during the discharge of lithium air batteries. Yang Shaohong said, "our newly manufactured blanket like material has more than 90% of the pore space, and its energy density is four times that of lithium-ion batteries of the same weight. Last year, we have proved that carbon particles can be used to make effective electrodes for lithium air batteries, but at that time, the carbon structure only had 70% of the pore space"

scientists pointed out that because the arrangement of carbon particles in this carbon fiber electrode is very orderly, while the carbon particles in other electrodes are very chaotic, it is easier to use scanning electron microscope to observe the behavior of this electrode in the middle of charging, which helps them improve the efficiency of the battery and explain why the performance of the existing system will decline after multiple charging and discharging cycles. However, the commercialization of this carbon fiber lithium air battery needs further research

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