New material makes lithium-air batteries more durable

The lithium-air battery model developed by researchers has a storage capacity of about 3,000 Wh/kg, which is about 8 times that of existing lithium batteries. It can be charged and discharged thousands of times, and the first cycle charge and discharge efficiency is as high as 93%. , that is, 93% of the energy charged into the battery can be used during discharge. If electric vehicles are to match the driving range of fossil fuel vehicles, their batteries will need to store more energy. Of these, lithium-air (lithium-oxygen) batteries are the best candidate, but there have been serious hurdles. Now, chemists at the University of Cambridge in the UK have developed a more durable design method that offers hope of overcoming these problems, taking the technology a big step closer to practical use. Yury Gogotsi, a materials chemist at Drexel University in Philadelphia, Pennsylvania, said the battery, designed by Clare Grey of Cambridge and her colleagues, is a small laboratory prototype that is a long way from a car battery pack, but is still a long way off. Their innovative combination of materials solves several important lithium-oxygen technology problems. The work, published in the Oct. 30 issue of Science, does look interesting, Gogotsi said, but he stresses that it's still just good science lab work on a small battery, not Move closer to market technology.Also read:https://www.aimeno.com/lithium-battery/221.html Lithium-air batteries, also known as breathing batteries, harness the energy that emerges from the reaction between lithium metal and oxygen in the air. In the past 20 years, lithium-air batteries have been extensively studied around the world. Typically, such batteries use lithium metal as the negative electrode material, and the positive electrode is a porous, conductive carbon material. During discharge, the lithium ions from the negative electrode react with the oxygen in the air at the positive electrode to produce a solid product called lithium peroxide, which fills the pores of the carbon electrode. When charging, the chemical process is reversed and the lithium peroxide is broken down to release oxygen. The storage capacity of this battery is theoretically 10 times that of lithium batteries currently on the market, but there are several major defects in practical applications. According to reports, the reaction product lithium peroxide and the reaction intermediate product lithium superoxide of lithium-air batteries have high reactivity and will decompose the electrolyte. Therefore, the battery power will drop sharply after several charge and discharge cycles, and the battery life will be short. ;Due to the poor conductivity of lithium peroxide, it is difficult to decompose during charging, and a high charging voltage is required, which will also lead to side effects such as decomposition of electrolyte and carbon electrodes; during discharge, lithium peroxide will block porous carbon electrodes, resulting in early discharge End; when charging, the surface of the lithium metal negative electrode will grow to the positive electrode in the form of dendrites, which may eventually lead to a short circuit, posing a safety hazard; lithium metal will react with water vapor, nitrogen, and carbon dioxide in the air, resulting in the consumption of negative electrode materials, and eventually the battery will be damaged. invalidated. In this latest work, the researchers switched to multi-layered macroporous graphene as the cathode material, using water and lithium iodide as electrolyte additives, and eventually lithium hydroxide emerged and decomposed, rather than as in previous batteries. lithium oxide. Lithium hydroxide is more stable than lithium peroxide, which greatly reduces side reactions in the battery and improves battery performance. Among them, lithium iodide, in addition to helping to decompose lithium hydroxide, seems to also play a role in protecting the lithium metal negative electrode, making the battery immune to excess water. Without it, the same amount of water will directly invalidate the battery, completely unable to charge and discharge. The lithium-air battery model developed by the researchers has a storage capacity of about 3,000 Wh/kg, which is about 8 times that of existing lithium batteries. 93% of the energy in the battery can be used during discharge. The researchers pointed out that this work provides many new ideas for accelerating the development of lithium-air batteries, such as using multi-layer macroporous graphene electrodes and electrolyte additives to change battery reaction products, reduce battery side reactions, and improve storage capacity. Also read:https://www.aminobattery.com/lithium-battery/