A design of Nafion-coated bilayered quasi-solid electrolyte for lithium-O2 batteries with high performance

Abstract

In this paper, a novel bilayer-structured quasi-solid polymer electrolyte (NSPE) has been designed with separate catholyte and anolyte, which compose of P(VDF-HFP)/Li-Nafion solid polymer electrolyte and TEMPO as cathodic additives. The SEM images shows that the surface morphology of NSPE is smoother and more uniform than that of SPE. The Li-O2 battery using NSPE showed high ionic conductivity, low interface impedance, good rate performance, and higher security and good cycling stability while reducing polarization. Lithium-air (also known as lithium-oxygen) batteries have attracted considerable global attention in recent years due to their extremely high energy density (11,140 W·h·kg −1 ). The electrolyte is a key element in lithium-air batteries and the traditional organic electrolyte has great safety risk due to leakage. On the contrary, the polymer electrolyte has the advantages of high safety, high stability and easy processing comparing with the organic liquid electrolytes. In this paper, a new idea was proposed to coat the Nafion membrane on a layer of polymer for blocking the oxidation reduction electric (RM) and Li based on the selective permeability on lithium ion of the Nafion membrane. Self-made thickness-controllable Nafion membrane, polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) and 2,2,6,6-tetramethylpiperidinooxy (TEMPO) were used to prepare a quasi solid polymer electrolyte (NSPE). Electrochemical workstation and LAND battery testing system were used to perform a galvanostatic charge/discharge test on Li-O 2 . The ionic conductivity of NSPE was 4.3 × 10 −4 S·cm −1 at room temperature and the discharge platform was 2.6 V and the charging voltage was 3.7 V after 50 cycles with the cut-off capacity of 500 mA·h·g −1 .