PMMA-LiTFSI based gel polymer electrolyte for lithium-oxygen cell application

Abstract

In this work, poly (methyl methacrylate), PMMA based gel polymer electrolytes (GPEs) have been studied. Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was selected as lithium-ion donor and tetraethylene glycol dimethyl ether (TEGDME) as a solvent. The highest conducting sample was obtained at 25 wt% LiTFSI with ionic conductivity value of 2.80 mS cm −1 . The dielectric constant of GPEs sample follows the conductivity trend. The percentage of free ions is observed to increase up to electrolyte containing 25 wt% LiTFSI salt. Beyond that, the free ions percentage decreased. Lithium-ion transference number for the highest conducting sample is 0.47. The highest ionic conducting sample show good electrode-electrolyte interfacial stability and is suggested suitable in lithium-oxygen batteries. The charge and discharge capacities in the first cycle were 0.87 and 1.23 mAh cm −2 , respectively. Formation of Li 2 O 2 can be observed by XRD pattern of the air cathode during the discharge. • Large anion size contributes to enhance the ionic conductivity and lithium transference number. • A gel polymer electrolyte based on PMMA is a viable candidate for use as the electrolyte in a lithium-oxygen battery. • The discharge capacity retention of lithium-oxygen cell is 26 % after five cycles.