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(source: Argonne official website) according to foreign media reports, researchers from Argonne National Laboratory of the U.S. Department of energy have developed a new electrolyte mixture and a simple additive, which can increase the surface and overall stability of the silicon negative electrode, and is expected to be applied to the next generation of lithium ions. 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, cheaper and safer. With a new generation of batteries, electric vehicles are expected to be further popularized, and the expansion of the power grid to renewable energy will be accelerated through more cheap and reliable energy storage. For scientists, silicon anode has become the preferred material to replace the current graphite anode. Theoretically, silicon has obvious energy storage advantages, and its lithium storage capacity is almost 10 times that of graphite. Moreover, this kind of material has low cost and more commercial attraction. 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, a senior chemist at the Argonne Department of chemical science and Engineering (CSE), pointed out that "there are still some obstacles in the application of silicon anode. In the process of circulation, the silicon-based negative electrode of lithium-ion battery reacts violently with the electrolyte. If you live with it for a long time, it will lead to battery degradation and shorten cycle life. " At present, the solvent mixture in the electrolyte of lithium-ion battery includes a dissolved lithium salt and an organic additive (usually more than three, at least one). Argonne's scientists have proposed a new strategy for the unique design of electrolyte additives so that a small amount of another salt contains a divalent or trivalent metal cation, such as Mg2 +, Ca2 +, Zn2 +, or Al3 +. This kind of enhanced electrolyte mixture, collectively referred to as "mesa" (mixed salt electrolytes for silicon anodes), can increase the surface and overall stability of silicon anode, improve long-term cycle and service life. Baris key, a chemical technician in CSE, said: "we have fully tested mesa with a complete battery with standard commercial electrodes. The new chemical has simple structure, scalability and full compatibility with existing battery technology. " Vaughey added, "in this project, Argonne's battery analysis, modeling and prototyping (cAMP) facilities benefit us a lot and help us understand the material composition of mesa." Meanwhile, Argonne researchers focused on the working process of mesa electrolyte. During the charging process, the metal cation additive in the electrolyte moves to the silicon-based negative electrode with lithium ion, forming the lithium metal silicon phase, which is more stable than the lithium silicon phase. In the chemical reaction process of new battery, there are few harmful side effects between silicon anode and electrolyte. It has been proved that among the four metal salts tested in the battery, the electrolyte salt with Mg2 + or Ca2 + has the best effect in hundreds of charge discharge cycles. The energy density of this kind of cell is 50% higher than that of the same kind of graphite cell. "Based on the test results, we have every reason to believe that this invention will play a driving role in replacing graphite with silicon negative electrode, or forming a negative electrode together with graphite (concentration is slightly higher than that of graphite by several percentage points), which may have far-reaching impact," key said