American scientists discover new electrolyte materials

According to foreign media reports, scientists are looking for new chemicals, which can improve the energy density and performance of the battery, so that this battery can surpass the traditional lithium-ion battery.

One type of battery is a lithium-sulfur battery with higher energy density and lower cost. Compared with the traditional graphite / metal oxide lithium ion battery, the parasitic reaction occurring inside this battery will damage its performance and hinder its efficient cycle.

Scientists at the US Department of Energy's Argonne National Laboratory have discovered an electrolyte material. When charging lithium-sulfur batteries, an inevitable side reaction often occurs-lithium polysulfide Things shuttle. When the battery is discharged, lithium sulfide will be converted to sulfur on the cathode, but some lithium sulfur compounds that have not been fully oxidized will dissolve in the cathode and enter the liquid area of ​​the battery that separates the two electrodes-in the electrolyte, lithium sulfur compounds will It diffuses and reduces on the anode and oxidizes on the cathode. This process will be repeated over and over again, wasting battery power.

A large part of the reason for the polysulfide shuttle is that the polysulfide is easily dissolved in an electrolyte composed of a mixture of dioxolane (DOL) and dimethoxyethane (DME) compounds . The researchers said: "We need to solve two problems at the same time-so that it has both low solubility and high conductivity."

According to the researchers, in the past five years or so, a new electrolyte material has been developed to solve the above two problems. This kind of material is called hydrofluoroether (HFE), which has low dissolving power and still maintains good electrical conductivity. The researchers said: "The first step in reaching the anode of lithium is to dissolve in the electrolyte, just like water is a good solvent for common salt, DME is also a good solvent for lithium. However, With HFE, it is like dissolving salt in gasoline (difficult to dissolve). "

Although it was known that HFE possessed this trait a few years ago, the researchers proposed a method to predict the dissolution behavior and conductivity of such molecules. First, they divided HFE into three categories based on their chemical structure. When measuring how the electrolyte behaves, the researchers found that the chemical with the lowest solubility and the least amount of polysulfide shuttle has a lower conductivity. (Author: Rosanna quiet)