Improvement of Cycle Life of Lithium Air Batteries Using Ag and Mg Alloyed Li Anode

Abstract

Lithium-air batteries have attracted great interest due to great theoretical specific energy of Li-air excluding oxygen is 11.5 kWhkg−1, the value of which is comparable with that of gasoline/air device. This high energy density battery has the potential to be the power source for the advanced electric vehicles. However, there are a lot of challenges, one of which is low cycleability of lithium-air batteries because of formation dendrites on lithium anode and most significantly very high corrosion of lithium metal when room temperature ionic liquids (RTILs) are used. In this study, it was aimed to increase corrosion resistance therefore, cycleability of anode materials in Li-air battery cells by using mechanical alloying with silver and magnesium powders. The effect of the silver and magnesium on the electrochemical behavior of lithium anode for lithium-air batteries were investigated. Fine granules of Li metal and silver or magnesium were used as starting materials. At the first step the production of the Li-Ag and Li-Mg alloys was optimized in the mechanical alloying process. Subsequently, Li-Ag or Li-Mg powder alloys were synthesized as anode materials. The high energy ball milling was performed under argon atmosphere at room temperature. The alloys produced by mechanical alloying were cold pressed to produce dense lithium alloys. The physical characterization of the produced anodes was evaluated by X-ray diffraction (XRD) and scanning electron microscopy(SEM). Electrochemical analysis of the lithium and lithium alloys were carried out using a Swagelok-type cell with 1 M LiPF6 in TEGDME as electrolyte and GDL (gas diffusion layer) as cathode and prepared Li-Ag and Li-Mg powders as working anode. The electrochemical impedance spectroscopy (EIS) measurement of the lithium and alloys have been conducted to investigate the difference in the resistance of the cell before and after electrochemical cyclic test.