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2022-07-28
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American scientists have developed a new type of carbon fiber lithium air battery

American scientists have developed a new type of carbon fiber lithium air battery, whose energy density is now widely used in cars and rechargeable lithium 1 The research was published in the latest issue of energy and environmental science

last year, the research team led by yangshaohong, 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 bulky solid electrode. The carbon electrode can store energy by capturing oxygen from the air floating above it. The combination of oxygen and lithium ions will form lithium oxide

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

this has largely limited the development and progress of related industries.

Robert Mitchell, the collaborator of this paper and a graduate student of MIT's Department of materials science and engineering, 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."

another researcher, beta Galante, a graduate student of MIT Mechanical Engineering Department, explained that during the discharge process, lithium peroxide particles will appear on the carbon fiber, 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. Yangshaohong said: "the materials we have newly made, like blankets, have more than 90% of the pore space, and their 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 the carbon structure at that time only had 70% of the pore space."

the 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 a scanning electron microscope to observe the behavior of this electrode in the middle of charging, which helps them to improve the efficiency of the battery and explain why the existing system after multiple charging and discharging cycles, The performance will decrease if the conveying speed exceeds the reasonable range. However, the commercialization of this carbon fiber lithium air battery, most of which are toxic organic solvents, needs further research

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