Performance of Zn/Graphite rechargeable cells with 1-ethyl-3-methylimidazolium trifluoromethanesulfonate based gel polymer electrolyte

Abstract

There is an urgent need to fulfill the global thirst for energy in an efficient and safer way. Since long ago, Li based devices have been employed to cover up the high rising energy demand in the society. But, upon the realization of the hazardous nature and the cost of Li, a substantial attention has been focused on exploiting ecofriendly and naturally abundant materials to be employed for fabricating devices such as rechargeable cells, fuel cells, solar cells and super capacitors. Main aim of this study is to design a low cost, environmental friendly, rechargeable cell. Hence, attempts have been taken to use non Li based electrodes and a gel polymer electrolyte (GPE) with no solvents. The cell consists with natural graphite and Zn electrodes and an ionic liquid (IL) based GPE. ILs are the most recently introduced substitute for solvents in GPEs which possess some attractive features. For the preparation of the GPE, poly(vinylidinefluoride-co-hexafluoropropylene) (PVdF-co-HFP), zinc trifluoromethanesulfonate (Zn(CF3SO3)2 and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (1E3MITF) were used as the polymer, the salt and the ionic liquid (IL) respectively. Configuration of the fabricated cell was Zn/IL based GPE/graphite. Cells had an average open circuit voltage (OCV) value of 1.10 V. Variation of OCV with time was quite low. Cells were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) as well as continuous galvanostatic charge discharge (GCD) test. Properties of the bulk electrolyte as well as electrode/electrolyte interface were rather stable. Average specific charge was remaining around 4 mAhg–1. Discharge capacity was varying around 2 mAhg–1. These results reflect the possibility of using this cell for applications with some further modifications to increase the performance.