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The battery is charged and discharged by "breathing" oxygen, and it's fresh. On February 19th, the reporter learned from the Institute of Green Energy of the Chinese Academy of Sciences that the team had made breakthroughs in the research of “lithium-air batteriesâ€. Through the study of catalysts, the efficiency of combining and decomposing lithium with oxygen in the air was greatly improved, and thus the charge was increased. Discharge efficiency lays the foundation for its commercial application as soon as possible, and it is expected to become the ideal power source for future electric vehicles.
One charge is expected to run 800 kilometers
“The research and application prospects for lithium-air batteries are very broad.†On February 19, Cui Guanglei, researcher of Bionic Energy and Energy Storage System of the Chinese Academy of Sciences Green Energy Institute, briefed reporters on the new progress made by their team in lithium-air battery research.
Lithium batteries are all very familiar with, then what is a "lithium-air battery"? It is understood that lithium air battery is a new type of metal air battery, Cui Guanglei said that the theoretical energy density of lithium air battery is 5200Wh/kg, there is a high battery system 1 to 2 orders of magnitude, that is to say the unit of battery discharge Electricity is tens or even hundreds of times that of other batteries.
It is understood that the future demand for power energy density of electric vehicles is 700Wh/kg, and lithium-air batteries can fully meet this requirement. It is expected to be able to drive 800 kilometers on one charge.
The application prospect is broad, but at present the study has not been used in practical applications. "It has a great relationship with all aspects of the cost, because to achieve good results, the best catalytic material at present is gold, platinum, etc. The cost is too high.†The team of bionic energy and energy storage systems of the Chinese Academy of Sciences Green Energy Institute made a breakthrough in the research of lithium-air battery electrode materials. The new electrode materials they developed can improve lithium-air batteries in deep discharge. The circulatory capability laid the foundation for the commercialization of this attractive power system as soon as possible.
The battery recharges by "breathing" oxygen
We all know that batteries have positive and negative electrodes. What are the positive and negative electrodes of lithium-air batteries? Cui Guanglei said that the positive and negative electrodes of a lithium-air battery are in its name, metallic lithium is its negative electrode, and positive electrode is oxygen in the air.
“The working principle of a lithium-air battery is very simple. During the discharge process, oxygen molecules combine with lithium ions to form lithium peroxide; during the subsequent charging process, lithium peroxide reversibly decomposes to generate oxygen. This process is very biological.†Breathing process: Inhalation of oxygen, oxygen and organic matter and water and carbon dioxide, release energy, provide biological life energy; and water and carbon dioxide produce organic energy stored through the photosynthesis of plants, release oxygen.
Cui Guanglei said that oxygen has too many benefits as a positive electrode for lithium-air batteries, because oxygen is widely distributed in the air and is easily available, greatly reducing the cost of batteries, and has no pollution to the environment. The energy density of such batteries is also very high. This kind of technology is put into commercial application, then the future electric vehicle will have the ability to be able to compete with traditional fuel vehicles."
"Generalist" catalyst can swallow
How is the battery's "breathing" accomplished? This has to mention the team's core research - catalyst. In the lithium air battery schematic diagram that this team studies, the reporter saw this kind of battery divides into three layers, lithium, electrolyte, catalyst. Oxygen is in the catalyst layer into the battery and react with lithium ions, "The role of the electrolyte is to allow lithium ions to pass smoothly but does not cause a short circuit between positive and negative." And the key to let lithium and oxygen "marriage" is Catalyst layer.
According to reports, lithium-ion batteries currently have two core issues, such as low efficiency of charge and discharge energy conversion and short cycle life of deep discharge. The team is focused on this issue to find the key to restricting two issues: catalyst materials. "We have found that transition metal nitride properties are very suitable." This has also become the breakthrough point for the research. The team designed and synthesized cobalt molybdenum nitrogen ternary materials with double-effect catalytic properties by introducing cobalt into nitride materials. "It is said to be double-acting catalysis, which is similar to 'all-rounder'. It catalyzes both discharge and catalysis, and its characteristics are very obvious."
Cui Guanglei said that they designed the catalyst into a nanostructure, increased the area of ​​catalytic reaction, formed a high-performance lithium-air battery cathode, successfully reduced the charge and discharge polarization of the battery, improved the energy conversion efficiency, and greatly improved the lithium-air battery Cycle life at deep discharge. A series of studies increased the cycle life of lithium-air batteries by 70%.
Expected to help replace automotive fuel
With the soaring price of fossil fuels, the replacement of petroleum products with high-efficiency power supplies to provide power support for motor vehicles has become an urgent requirement for the development of modern society. Lithium-ion batteries have always been considered the best candidates for electric vehicles. However, the battery life of electric vehicles based on lithium-ion batteries still cannot meet people's needs because the energy density of lithium-ion batteries is still lower than that of gasoline combustion. Lithium-air batteries, as an ideal replacement for lithium-ion batteries, still have 10 times more capacity than the best-performing lithium-ion batteries. "Our research has been going on for more than three years. The most difficult thing is to look for this kind of material," said Cui Guanglei. The current result is also the result of their many years of struggle. It is of great significance. The study was supported by key projects such as the Chinese Academy of Sciences, the National Natural Science Foundation of China, the Shandong Province Jieqing Fund and the Qingdao Key Laboratory of Solar Energy Storage Technology, and has achieved a number of important research results.
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Lithium-ion batteries and lithium-air batteries
Lithium-ion batteries are widely used in mobile phones and notebook computers, etc. It is based on lithium compounds for the positive electrode, carbon materials for the negative electrode, higher density than other automotive batteries, electricity is more abundant, but more expensive, subject to the battery capacity, The distance traveled after charging is still not far enough. It is generally believed that in order to achieve the popularity of electric vehicles, the energy density needs to reach about 6 to 7 times the current level. As a result, metal lithium air batteries with theoretically much higher energy densities than lithium-ion batteries have attracted much attention.
Scientists believe that the performance of lithium-air batteries is 10 times that of lithium-ion batteries and can provide the same energy as gasoline. Lithium-air batteries absorb oxygen from the air, so the batteries can be smaller and lighter. Many laboratories around the world are researching this technology, but if there is no major breakthrough, it may take some time to realize commercialization. Reporter Li Xiaozhe
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