Is the instability of lithium batteries the reason for the electrolyte?

When you want your mobile phone the most, are you worried that it won't work? When you drive an electric car, what should you do when the car is out of power? Regarding these questions, a portable lithium-sulfur battery can answer you! Its energy storage capacity is more than twice that of the batteries on supermarket shelves, but it often appears that there is no electricity and the service life is not long. Scientists at the Joint Center for Energy Storage Research (JCESR) and the Pacific Northwest National Laboratory have discovered one of the reasons behind this problem. They found that the salts used in the electrolyte in the battery made a big difference. When a salt called LiTFSI (Lithium bis(trifluoromethylsulfonimide)) is made into the battery electrolyte, the probe battery can maintain the maximum charge and discharge capacity and run more than 200 times. In lithium-sulfur batteries, LiTFSI confines lithium and sulfur atoms on the electrodes, but releases them soon. In contrast, a similar electrolyte has stronger binding force on lithium and sulfur atoms and does not release at all. The result is a rapid decline in battery performance; after running the battery dozens of times, there is no energy. One of the concerns of electric vehicles is that when driving on the highway for a long time, the driver does not want to be trapped between charging stations. This concern makes consumers decide to buy low-displacement cars. The results of this study added another important factor to the design command of high-energy lithium-sulfur batteries. In order to determine the impact of the electrolyte on the lithium-sulfur battery, the research team used LiTFSI and LiFSI for related experiments. LiTFSI and LiFSI are two very similar electrolytes, except that LiFSI contains less carbon and fluorine than LiTFSI. They used the equipment in the environmental molecular laboratory to continuously detect the energy of battery charging and discharging, and finally investigated and decomposed the electrodes. They found that in lithium-sulfur batteries using LiTFSI as the electrolyte, lithium atoms are bound by sulfur atoms, forming lithium sulfide (LiSx) on the surface of the electrode. When LiFSI is used as the electrolyte, lithium sulfate (LiSOx) is formed. By calculating the tightness of the combination of two lithium compounds, they found that lithium sulfide is easily broken to release lithium. However, lithium sulfate is difficult to separate, so the oxygen element in lithium sulfate is the culprit. By combining the macroscopic component decomposition and simulation, we can see what bonds are easy to break, and what happens if the chemical bonds are broken. Dr. Ji-Guang (Jason) Zhang, who is leading the research at the National Laboratory, said that this process allows us to identify the behavior of electrolytes, guide us to design better electrolytes, and improve the cycle life of lithium-sulfur batteries. For researchers, the next step is to study electrolyte additives to form a protective layer on the surface of the lithium anode to prevent corrosion from the electrolyte. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: What are the important performance indicators of lithium batteries