A High-Stability Lithium-Air Battery Using Electrolyte Doped with PFDL

At present, most of the research on lithium-air batteries (LABs) is carried out in a dry pure oxygen environment, and their working stability still needs to be further explored in the air environment. In this paper, the synergistic effect of perfluoronaphthane (PFDL) was added to the organic electrolyte (LiTFSI-TEGDME) of LABs. An oxygenating additive was systematically studied to improve the working stability of the battery in the air environment. The electrochemistry of LABs doped with PFDL electrolyte was studied by cyclic voltammetry, electrochemical impedance spectroscopy, a constant current and constant volume charge-discharge test, and deep charge-discharge test. At the same time, scanning electron microscopy and x-ray diffraction analysis were used to characterize the air cathode before and after the operation. The results showed that the best volume ratio of electrolyte to PFDL is 7:3. Under the condition of the charge-discharge current density of 100 mA cm(-2), 136 cycles (1360 h) of lithium-air battery using PFDL mixed electrolyte in the air environment were achieved, which was about 5.5 times that of LABs with basic electrolyte, which is close to the cycle times of a battery in pure oxygen under the same conditions. At the same time, the specific capacity of the battery at first discharge reached 4730 mAh g(-1). In addition, based on experiments, combined with simulation software, we established a mesoscopic mass transfer model to further verify the influence of adding PFDL into electrolytes on oxygen mass transfer and diffusion. Experimental and simulation results show that PFDL has excellent oxygen solubility and good hydrophobicity. It optimizes the oxygen transmission in the battery, makes the LABs more stable in air, and provides a wider space for the application of PFCs in LABs.