Fluorinated Aromatic Diluent For High-Performance Lithium Metal Batteries

The high-concentration lithium salt electrolyte has very excellent physical and chemical properties, which is conducive to improving electrode stability and battery coulombic efficiency, and improving rate performance and safety performance of lithium batteries. However, increasing the concentration of lithium salt in the electrolyte also greatly increases the cost of the electrolyte, and high cost is one of the important factors that limit the commercial application of high concentration lithium salt electrolyte.

In order to further promote the application of high-concentration lithium salt electrolyte and meet the development needs of large-scale energy storage, scientists have proposed the concept of "diluting high-concentration electrolyte", that is, without affecting the electrochemical performance of high-concentration electrolyte Above, the concentration of lithium salt in the high-concentration electrolyte and the viscosity of the electrolyte are reduced by the diluent. At present, ether solvents have been used to dilute high-concentration lithium salt electrolytes.

Recently, Korean scientists have made new progress in the research of high-concentration electrolyte diluent. They have developed a new type of fluorinated aromatic electrolyte diluent, namely 1,2-difluorobenzene, which can ensure high concentration effect under the premise of reducing the actual lithium salt concentration in the electrolyte.

1,2-Difluorobenzene has a low dielectric constant and high fluorine content at the molecular level. As a diluent, it can not only induce the formation of high concentration effects, but also promote the formation of LiF-rich SEI films, which can be active The metal lithium is passivated, thereby inhibiting the growth of lithium dendrites. In addition, the researchers found that through the use of suitable lithium salts and electrolyte additives combined with 1,2-difluorobenzene can achieve the matching of metal lithium anodes and 4V grade cathodes, and improve the stability of the electrochemical properties of metal lithium batteries.

This research provides a new idea for the design of high-concentration lithium salt electrolyte, which is helpful for the development and application of high-performance lithium metal batteries.

References: Dong-Joo Yoo, Sungyun Yang, Ki Jae Kim, Jang Wook Choi. Fluorinated Aromatic Diluent for High-Performance Lithium Metal Batteries, Angewandte Chemie International Edition, 2020.DOI: 10.1002 / anie.202003663