Lithium-air battery is a battery that uses lithium as the negative electrode and oxygen in the air as the positive electrode reactant. Li-air batteries have a higher energy density than lithium-ion batteries because the cathode (mainly porous carbon) is light, and oxygen is obtained from the environment without being stored in the battery.
Discharge process: The lithium in the negative electrode releases electrons and becomes lithium cations (Li+). Li+ passes through the electrolyte material and combines with oxygen and electrons flowing from the external circuit to form lithium oxide (Li2O) or lithium peroxide (Li2O2). And stay on the positive electrode. The open circuit voltage of the lithium-air battery is 2.91 V
In theory, since oxygen is not limited as a positive electrode reactant, the capacity of the battery depends only on the lithium electrode, and its specific energy is 5.21kWh/kg (including the mass of oxygen), or 11.4kWh/kg (not including oxygen). Compared with other metal-air batteries, lithium-air batteries have a higher specific energy (see the table below), so it is very attractive.
According to overseas media reports, a few days ago, researchers at the Argonne National Laboratory in the United States announced that a new breakthrough has been achieved in the field of lithium oxide battery technology. Scientists from the United States and South Korea jointly demonstrated the development based on lithium superoxide (LiO2) Lithium-air battery.
According to a report published in "Nature" magazine, the advent of lithium-air batteries will create a precedent for high-energy-density batteries developed based on lithium superoxide, and also provide the possibility of other uses for compounds such as oxygen storage materials.
During the chemical reaction, lithium-air batteries can form lithium peroxide (Li2O2). Lithium peroxide is a solid precipitate used to block electrode pores and reduce battery performance. It is also an indispensable part of the charge-discharge reaction process. .
Previously, industry insiders have pointed out that lithium-air battery technology still needs to overcome many difficulties, and it will take at least 10 years to put it into commercial use. However, a large number of research results indicate that both lithium superoxide and lithium peroxide formed by lithium-air batteries can be used as important components of discharge products.
Unlike lithium peroxide, superoxide can be easily decomposed into lithium ions and oxygen ions, thereby improving work efficiency and extending battery cycle life. In addition, theoretical calculation results show that some forms of lithium superoxide have a longer life.
During the experiment, the iridium atoms contained in the electrodes used by the researchers were separated, so that the amount of lithium superoxide kept rising.
Scientists Larry Curtiss and Khalil Amine of Argonne National Laboratory explained that batteries developed based on lithium superoxide can at least theoretically be made into lithium-air batteries composed of a closed system. Open systems often need to continuously take in oxygen from the external environment, while closed systems do not. The latter can also make the battery safer and more efficient.
At the end of last year, Professor Clare Grey and her team at the University of Cambridge in the United Kingdom also overcome the difficulties in the development of lithium-air battery technology. The team concluded that in theory, the energy density of lithium-air batteries can reach 10 times that of current rechargeable lithium-ion batteries on the market, the battery efficiency is as high as 90%, and the number of recharges can reach 2,000 times.