Research finds that enhanced SEI can improve the energy safety of lithium metal batteries

by:CTECHi     2021-07-27

According to foreign media reports, researchers at Penn State University in the United States said that using a newly developed solid electrolyte interface membrane (SEI), rechargeable lithium metal batteries can achieve higher energy density, better performance and Better security.

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With the increasing demand for higher energy density lithium metal batteries such as electric vehicles, smart phones and drones, the instability of SEI has become the key to hindering the development of lithium metal batteries The problem is that a salt layer on the surface of the lithium electrode of the battery will isolate the SEI and conduct lithium ions.

As the most unknown part of lithium metal batteries, the degradation of SEI promotes the formation of dendrites. Dendrites are a needle-like structure that grows from the lithium electrode of the battery, which will have a negative impact on the performance and safety of the battery.

Wang, a professor of mechanical and chemical engineering, said: This is why the life of lithium metal batteries is not long. Once the interface film grows, the battery will become unstable. In this project, we used polymer composite materials to create a better SEI. The project is led by YueGao, a PhD student in chemistry. The enhanced SEI developed is a reactive polymer composite material composed of polymer lithium salt, lithium fluoride nanoparticles and graphene oxide sheets. The structure of the new battery module contains one layer. Thin such materials.

The polymer developed by the researchers can form a claw-like bond with lithium metal, which passively supplies the required energy to the lithium surface so that it will not interact with the electrolyte. The molecules react, and the nanosheets act as a mechanical barrier in the composite material to prevent the formation of dendrites in the lithium metal.

Through chemical and engineering design and cooperation, this technology can control the lithium surface at the atomic level. In addition, the reactive polymer also reduces the weight of the battery, reduces the manufacturing cost, and further promotes the future development of lithium metal batteries. In 2018, the sales volume of Formosa Plastics Mitsui's electrolyte increased 4.5 times compared with the same period in 2017. During the Japan Smart Energy Week on February 27-March 1, Zhang Shiqiang, the sales director of Formosa Plastics Mitsui, accepted an exclusive interview with OFweek Lithium Grid, and said this when answering questions about last year's performance. The performance of Formosa Plastics Mitsui in 2018 is really impressive. So, how did Formosa Mitsui do it? What are the advantages relative to other peers? What is the plan for 2019?

Forms Plastics Mitsui: strong strength boosts business performance

Forms Mitsui is a subsidiary of Japan’s Mitsui Chemicals and Taiwan Plastics Industry The joint venture company opened an electrolyte production plant in Ningbo, Zhejiang in 2013. Mitsui Chemicals started the electrolyte business in 1995 and has more than 20 years of technology and related experience accumulation. Mitsui Chemicals has a subsidiary specializing in analysis, which is able to conduct the most advanced analysis of lithium-ion batteries. Zhang Shiqiang believes that since the establishment of Formosa Plastics Mitsui, it has attached great importance to production management and safety environment, used the rich experience and knowledge related to electrolyte and lithium-ion batteries, and used the high analytical ability of lithium-ion batteries to solve the problem of many customers’ battery problems through the electrolyte. The problem.

In addition, according to OFweek Lithium Grid, the two parent companies are both comprehensive chemical groups and have the strong ability to independently develop new additives. So far, thousands of additives have been reviewed, and a variety of independently developed additives have been used in electrolyte products. Zhang Shiqiang gave an example to OFweek's lithium grid. The additive PST (propenyl-1,3-sultone), which is extremely effective for silicon-carbon negative electrodes and high-voltage ternary systems, is an additive developed by Mitsui Chemicals independently.

Strong Ru0026D strength and deep accumulation of relevant experience have enabled Formosa Plastics Mitsui to achieve a 4.5-fold increase in 2018 when the development of the industry is limited. What surprised us even more was that Zhang Shiqiang predicted that the sales volume of Formosa Plastics Mitsui's electrolyte would increase 3.5 times in 2019.

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