Brief introduction of high-performance lithium metal battery electrolyte

In the design of metal lithium secondary batteries, the performance of the battery highly depends on the amount of electrolyte and the charge and discharge current density. When the number of electrolytes is small, the mutual use between the metal lithium negative electrode and the NCM positive electrode will accelerate the electrolyte in the metal lithium negative electrode. Analysis and formation of a high-impedance SEI film. However, too much electrolyte will not only reduce the energy density of the battery, but also increase the cost of the battery. Therefore, the development of a more stable electrolyte to reduce the amount of electrolyte is particularly critical. The lithium metal negative electrode comes from FMC, and the electrolyte cycle performance of adding FEC and DFEC has been significantly improved. FEC+DFEC still maintained good cycle stability after 300 cycles. When the circulation temperature is increased to 45°C, the FEC+DFEC mixed solvent electrolyte still maintains the best cycle performance, and the rate performance of the electrolyte using FEC is better than that of DFEC and FEC+DFEC electrolyte. The electrolyte using the FEC+DFEC hybrid system shows better cycle stability, which can be stably cycled for more than 250 times, and the battery does not show the phenomenon of FEC battery capacity decline and then recovery. This is mainly because the FEC+DFEC mixed electrolyte system can form a more stable SEI film on the surface of the negative electrode. The battery using the FE+DFEC system electrolyte not only maintained good stability in capacity at the beginning of the cycle and after 200 cycles, but the battery's charge and discharge voltage also did not show a distinct decline. In the EC-based electrolyte, the SEI film is thicker and contains more PEO-like polymer components. This indicates that the reduction and polymerization of EC on the metal lithium surface during the cycle process causes the degradation of the metal lithium battery. The important reason. Compared with the EC solvent, the SEI film formed in the FEC solvent contains some organic components, but also contains some inorganic components such as lithium carbonate, lithium fluoride, lithium alkyl carbonate and other components. This composite SEI film is not only Endows the SEI film with good elasticity, can adapt to the volume change of metallic lithium, and also allows Li+ to quickly pass through the SEI film. There are a large number of lithium dendrites on the surface of the lithium metal negative electrode using the EC-based electrolyte. The dendrites greatly increase the surface area of u200bu200bthe lithium metal negative electrode and accelerate the analysis of the electrolyte. In contrast, the surface of the metal lithium negative electrode of the FEC and DFEC electrolytes presents flake metal lithium. Compared with needle-shaped lithium dendrites, the electrode has a smaller specific surface area, which effectively improves the cycle performance of the electrode. . 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 article: How to check the life limit of lithium battery?