Regulating the Interfacial Chemistry by Rationally Designed Multicomponent Electrolyte Additives To Enable Stable Ncm523/Graphite Pouch Cells

Abstract

The electrolyte is the blood of the battery, which determines the various performance of the battery. However, the current commercial electrolyte still cannot satisfy the normal operation of the battery under the conditions of high-temperature and high-voltage. Here, we design the multicomponent electrolyte additives (fluoroethylene carbonate (FEC), ethylene sulfate (DTD), and propane sultone (PS) ) (FDP) to improve the battery performance under extreme conditions. On this basis, we have studied the gas production and composition in the initial formation stage of the battery, and find that the addition of FDP can generate a large amount of C2H2 in advance, and form a thin, stable, uniform and dense, low impedance and elastic interfacial film on the electrodes. Meanwhile, the thickness expansion rate of modified battery is only 29.3%, while that of the original battery is 72.4% at 4.4V and 45°C. Furthermore, the 1700mAh-level NCM523/graphite pouch cell with FDP can achieve the capacity retention rate of 97.3% after 300 cycles at 4.4V and 45°C, which that of original cell is 26.7% after 77 cycles at this situation. The FDP-containing electrolyte may provide beneficial guidance for the design of commercial electrolytes for the Lithium-ion batteries.

Keywords: Lithium-ion batteries, fluoroethylene carbonate, ethylene sulfate, propane sultone, electrolyte additive