Air Cells, metal fuel cells open the door to a new world of mobile power

Al-air fuel cell is a new type of high energy chemical power source. The battery has the advantages of high energy density, light weight, abundant material sources, no pollution, high reliability, long service life, safe use and so on. Therefore stands out among the numerous batteries, by the world each country is generally good at. The United States, Canada, the Yugoslavia, India, Norway, the United Kingdom, Japan and other countries are actively engaged in research. Because of the successful development of air electrode with good performance, the research of aluminum-air fuel cell has made great progress. Great progress has been made in the field of middle, high power and low power al-air fuel cells in foreign countries. China's relatively late start, there are not many research institutions. The Harbin Institute of Technology has been engaged in the research of aluminum-air fuel cell since 1980s, the research work of anode quaternary aluminum alloy has been completed in 1983, and the sample preparation of 3W neutral aluminum-air fuel cell has been completed in 1990s, in 1993, a 1kW alkaline aluminum air fuel cell (AAFC) was developed. In the early 1990s, Tianjin University successfully developed the marine high power neutral electrolyte aluminum-air fuel cell stack, and has been engaged in the research of low power neutral electrolyte aluminum-air fuel cell for electric vehicle, some batteries are now entering commercial use. In the 1990s, the Wuhan University also did preliminary research on seawater aluminum air fuel cells. But in recent years, there have been fewer and fewer research institutions, and few reports. Therefore, this article on the current overseas aluminum air fuel cell research situation analysis and research report. 1 How an aluminum air fuel cell works, al-air fuel cell uses high purity aluminum (aluminum content 99.999%) or aluminum alloy as anode, oxygen (air) electrode as cathode, Alkali or salt as electrolyte. During the discharge the anode dissolves and the oxygen in the air is reduced to release electrical energy. According to the electrolyte, can be divided into alkaline (electrolyte is alkaline class) and salt (electrolyte is salt, generally brine) aluminum air fuel cell. Aluminum is the most abundant metal element on the earth, accounting for the third place in the element distribution, the global industrial reserves of aluminum has more than 2.5 ~ 1010t. For more than a century, aluminum has been the world's largest producer and most widely used Non-ferrous metal, with a total global output of 1.7107 tons in 1996. Therefore, the aluminum anode material source is rich. Aluminum is a reactive metal that is more attractive than metals like zinc or magnesium. Because aluminum has a high electrochemical equivalent of 2980 Ah/kg and a negative electrode potential, it is the metal with the highest mass-specific energy except lithium. The mass-specific energy of al-air fuel cell can reach 450 wh/kg, the volume-specific energy is less than that of lead-acid battery, and the specific power is 50 ~ 200 w/kg. Aluminum releases three electrons per atom, while zinc and magnesium release only two, and lithium one. That is to say, the amount of material needed to produce the same amount of energy, the least amount of aluminum. Therefore, aluminum becomes the best choice of anode material for metal-air fuel cell. Figure 1 shows the comparison of al-air fuel cells with other primary cell systems: zn-air, li-column, li-ion, alkaline, silver, mercury and zn-carbon. From the diagram, it can be seen that al-air fuel cells have the highest specific energy density of mass and volume, which is consistent with the very high specific power density of al-air fuel cells.