The Effect of Supply Rate of Li Ion and Anion on Li Dissolution/Deposition Behavior in LiNO₃ Electrolyte Solutions for Li-Air Batteries

抄録

Although Li-air batteries (LAB) have a high theoretical energy density (3500 Wh kg⁻¹), further developments are required to overcome their practical limitations. Regarding the Li-metal negative electrode (NE), we have previously reported on the reversibility of the Li dissolution/deposition reaction by using Li|Li symmetric cells with a tetraglyme (G4)-based electrolytic solution. Particularly, in the 1.0 M LiNO₃/G4 electrolyte under an O₂ atmosphere, a Li₂O protective layer is efficiently formed on the Li-metal electrode at a current density of 0.40 mA cm⁻², and Li dendrite formation is suppressed. In the present study, we expanded the test conditions (current densities up to 2.0 mA cm⁻² and temperatures of 10 to 50 °C) to clarify the dissolution/deposition behavior of the Li-metal NE. The effects of two electrolyte solutions, namely LiTFSI/G4 and LiNO₃/G4, on the Li-metal NE were evaluated based on cyclical testing using Li|Li symmetric cells under an O₂ atmosphere. The NEs were also examined by scanning electron microscopy and X-ray photoelectron spectroscopy. The results indicated that not only LiNO₃ salt but also the supply of Li and nitrate ions at the Li electrode surface are critical factors in LAB performance.