(Source: Agung official website)
According to foreign media reports, researchers from the US Department of Energy's Argonne National Laboratory have developed a new electrolyte mixture and a simple additive that can increase the surface and overall stability of the silicon anode, and are expected to be used in the next generation of lithium-ion batteries.
In order to produce a new generation of lithium-ion batteries, scientists have been searching for new electrode materials and electrolytes for decades. Their goal is to improve the battery's energy storage capacity, making it longer life, lower cost, and safer. With a new generation of batteries, electric vehicles are expected to further popularize and accelerate the expansion of the power grid to renewable energy through cheaper and reliable energy storage.
For scientists, silicon anodes have become the material of choice to replace current graphite anodes. In theory, silicon has obvious energy storage advantages, and its lithium storage capacity is almost 10 times that of graphite. Moreover, the low cost of this substance makes it more commercially attractive. As the second largest element in the earth's crust, silicon is widely used in computing and communication hardware, and has a series of processing technologies. However, Jack Vaughey, senior chemist at the Argonne Chemical Science and Engineering Department (CSE), pointed out, "There are still certain obstacles to the application of silicon anodes. During the cycling process, the silicon-based anodes of lithium-ion batteries react violently with the electrolyte. In this way, the battery will deteriorate and the cycle life will be shortened. "
Currently, the solvent mixture in the electrolyte of a lithium ion battery includes a dissolved lithium salt and organic additives (usually more than three, at least one). Argonne scientists have proposed a new strategy to uniquely design electrolyte additives so that a small amount of another salt contains a divalent or trivalent metal cation, such as Mg2 +, Ca2 +, Zn2 +, or Al3 +. Such enhanced electrolyte mixtures, collectively referred to as "MESA" (mixed-salt electrolytes for silicon anodes, representing mixed salt electrolytes for silicon anodes), can increase the surface and overall stability of silicon anodes and improve long-term cycle and service life. Baris Key, a chemist in the CSE department, said: "We conducted a comprehensive test of MESA through a complete battery with standard commercial electrodes. This new chemical substance has a simple structure, is scalable, and is fully compatible with existing battery technology."
Vaughey added, “In this project, Argonne ’s battery analysis, modeling and prototyping (CAMP) facilities have benefited us a lot and helped us interpret the material composition of MESA.â€
At the same time, Argonne researchers focused on observing the working process of the MESA electrolyte. During the charging process, the metal cation additives in the electrolyte, as lithium ions migrate to the silicon-based negative electrode, form a lithium metal silicon phase, which is more stable than the lithium silicon phase. In the chemical reaction process of new batteries, there are very few harmful side effects between the silicon anode and the electrolyte. It has been proved that among the four metal salts tested in the battery, the addition of Mg2 + or Ca2 + electrolyte salt has the best effect in hundreds of charge and discharge cycles. The energy density of this type of battery is 50% higher than similar graphite batteries.
Key said: "According to the test results, we have every reason to believe that this invention will play a role in promoting the replacement of graphite with silicon anodes, or together with graphite to form anodes (concentration slightly more than a few percentage points of graphite), and may produce far-reaching influence. "(author: Elisha)
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