U.S. universities cooperate with each other to make high-efficiency batteries using non-flammable electrolytes

by:CTECHi     2021-08-27
According to foreign media reports, a research team from Florida State University and Cornell University (CornellUniversityresearch) found that batteries can be made with cheap and safe components, and compared with the most advanced lithium-ion batteries. The efficiency is 2 to 3 times higher. A. Nijamudheen, Postdoctoral Research Institute of FAMU-FSU School of Engineering, along with Cornell University doctoral student Snehashis Choudhury, and other faculty members from the two universities, launched an investigation to study the current battery design defects and how to improve them. Choudhury said: 'It is not surprising to see battery costs increase over time. The widespread adoption of battery technology requires cost reduction.' In order to reduce costs, researchers have solved several specific problems related to electrolytes, which are the key to the battery structure. In part, it can promote the movement of ions from one electrode to another. The research team understood the chemical process of electrolyte degradation on battery electrodes. The researchers not only discovered the mechanism of electrolyte degradation, but also found a variety of solutions. Nijamudheen said: 'We have found that controlling the ionic properties of the interface (SEI) formed on the negative electrode is the key.' The researchers found through quantum calculations that the source of battery degradation lies in the way in which a component called diethylene glycol in the electrolyte polymerizes. . Polymerization is a process in which molecules combine chemically to form long-chain-like molecules called polymers. As far as batteries are concerned, after the electrolyte has been in contact with the positive and negative electrodes of the battery for a long time, it often splits and regenerates into larger molecules. The researchers said: 'Although the degradation process itself is harmless, the substances that are degraded will prevent ions from entering the battery electrodes, and over time, it will reduce the energy that the battery can store.' However, despite certain polymerizations in the degradation process Substances prevent ions from reaching the electrodes, but there is evidence that other types of polymers can effectively extend battery life. After performing the polymerization calculations, the researchers began to study other types of electrolytes that would not affect the battery performance during the polymerization process. Generally speaking, lithium-ion batteries are made of organic carbonate electrolytes, but such electrolytes are highly flammable, so in order to prevent battery thermal runaway and the risk of fire, it is necessary to supply expensive cooling and heat regulation components. Therefore, the researchers tested a non-flammable stable electrolyte-lithium nitrate electrolyte. Using this electrolyte, researchers began to experiment on the solid electrolyte SEI membrane. The SEI film is a protective layer formed by the decomposition of the electrolyte, which usually appears when the battery is first cycled. Researchers use sacrificial salts or new molecules introduced through electrolytes to naturally form a new type of SEI film in the battery. In addition, the researchers also introduced a chain transfer agent (a string of molecules) to interact with diethylene glycol to form a shield Layer to protect the negatively charged electrode from degradation. To evaluate the effectiveness of the design, the research team conducted a series of experiments on the battery's ability to use it, and then recharged the battery. It was found that this battery can be cycled about 2000 times, which is much higher than the 300 to 500 times of traditional lithium-ion batteries.
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