TU-TESL

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According to foreign media reports, researchers of skoltech, Russia, Institute for problems of Chemical Physics of RAS, Russian Academy of Sciences and Ural Federal University In collaboration with researchers at the University, it is confirmed that organic materials can be used to produce high-capacity and high-power materials without using lithium or other rare elements. In addition, the researchers also proved that the cathode material has very high stability, and the potassium battery made of it can charge and discharge rapidly and has high energy density. (photo source: Phys. ORG) now, lithium-ion batteries have become an indispensable part of daily life, widely used to store energy, especially for portable electronic products. With the continuous development of electric vehicles, more and more investment has been attracted, and the demand for batteries is also surging. For example, it plans to increase electric vehicle sales to 50% of total sales by 2025, while Daimler announced that it will stop developing internal combustion engines and focus on electric vehicles. However, a large number of lithium-ion batteries will lead to a serious shortage of resources for the production of lithium-ion batteries. Transitional metals such as cobalt, nickel and manganese are often used to make battery cathodes, which are rare, expensive and toxic. There are a few countries producing most of the less common lithium, but the global supply of lithium is too small to allow all traditional cars to be replaced by electric vehicles powered by lithium batteries. According to the German Centre for energy and Economic Research (FFE), lithium shortage may become a serious problem in the coming decades. Recently, scientists have proposed looking for alternatives such as sodium and potassium, which are chemically similar to lithium. Under the leadership of Professor Pavel Troshin, researchers at Skolkovo Institute of technology have made great progress in the research and development of sodium and potassium batteries based on organic cathode materials. In their first paper, the researchers mentioned a polymer containing fragments of hexaazatriphenylene. It has been proved that the new material can also be applied to lithium battery, sodium battery and potassium battery. The charging time is 30 to 60 seconds, and the energy storage capacity can be maintained after thousands of charging and discharging cycles. Roman kapaev, the first author of the paper and doctoral student of skoltech, explained: "versatility is one of the key advantages of organic materials. Compared with the characteristics of anti ions, their redox reaction mechanism is not so obvious, so it is easier to find alternatives for lithium-ion batteries. As the price of lithium continues to rise, it is reasonable to replace lithium with cheaper, never-ending sodium or potassium. As for inorganic materials, the situation will become more complicated. " The disadvantage of hexaazabenzophenanthrene polymer cathode is that the working potential is low (about 1.6V relative to K + / K potential), which leads to the decrease of energy storage capacity. Therefore, in the second paper, researchers mentioned another material, a polymer based on dihydrophenazine, which has no disadvantage of low working potential and can ensure the average working voltage of the battery to increase to 3.6V. Philip obrezkov, the first author of the paper and doctoral student of skoltech, explained: "aromatic polymers can be made into excellent high-pressure organic cathodes for metal ion batteries. In this study, we first used 5,10 dihydrophenazine in the cathode of potassium battery. The specific energy of 593 w × H / kg is achieved by optimizing the electrolyte thoroughly, which is the highest specific energy of all known potassium ion battery cathodes. " One of the main problems of metal ion batteries is the growth of metal dendrites, especially the batteries equipped with metal anodes. The growth of metallic dendrites in the cell leads to short circuit, fire and even explosion. In order to avoid this situation, alloy can be used instead of soda ash metal, because the alloy is liquid at the working temperature of the battery, which is also the view of 2019 Nobel Prize winner John B. goodenough. The melting point of K-Na alloy is low, 12.7 ℃ below zero, and the content of Na is about 22%. In the third study, scientists used a similar sodium potassium alloy on carbon paper as the anode of the battery, while the previously developed redox active polymer was used as the cathode. It is said that such batteries can be charged and discharged in 10 seconds. Interestingly, one polymer cathode makes the potassium battery reach the maximum energy capacity, while the other cathode makes the potassium battery have excellent stability, and only 11% capacity is lost after 10000 charging and discharging cycles. In addition, the batteries based on the two materials show unparalleled power characteristics, close to 100000 w / kg, reaching the power level of super capacitors.