In recent years, Li-air batteries (LABs) have attracted much attention as large-scale energy storage systems because of the high energy density over 5 times larger than that of the conventional Li-ion batteries. However, there are still some tough problems to be solved for both Li and air electrodes, of which we focused on the Li electrode. It is well-known that Li electrodes are apt to form dendrite deposit which might trigger short circuit failure or safety incidents. Therefore, we have been studying on dissolution/deposition of Li electrodes by using Li | Li symmetric cells [1], and reported that a Li2O protective layer formed on the Li electrode in 1.0 M LiNO3/tetraglyme under an O2 atmosphere efficiently suppressed the Li dendrite formation at 0.2 mA cm-2 [2]. In this presentation, we focus upon the effects of the current density and temperature on the morphology of Li electrode surface, particularly with respect to formation of Li2O protective layer and dendrite.LiNO3 (99.0%, KISHIDA) was dissolved in tetraglyme (G4, Japan Advanced Chemicals, H2O content < 30 ppm) in an Ar-filled glove box to prepare 1.0 M LiNO3/G4 electrolyte solution. Li dissolution/deposition tests were carried out at 10, 30 and 50°C at a constant current density between 0.2 and 2.0 mA cm-2. The surface of the Li metal electrodes and the cross-sections after the tests were observed and analyzed by SEM-EDS. The outermost surface of Li electrode was analyzed by using XPS.Fig. 1 shows the polarization curves for the Li dissolution/deposition tests in 1.0 M LiNO3/G4, which demonstrates the decreasing overvoltages of the Li dissolution/deposition reaction as the operating temperature increases. These results are attributed to the increased diffusion rate of Li+ ions in the electrolyte solution, and the reduced charge transfer resistance for the reaction. At 30 and 50 °C, the polarization curves show clear flatness and the overvoltages remain almost constant, which suggests suppression of dendrite deposits, and SEM images of the Li electrodes cycled at 30 and 50°C revealed no Li dendrites.However, the dissolution/deposition voltage profile at 10 °C shows poor flatness and decreasing overvoltages as cycling to suggest the formation of Li dendrites followed by the increase in the surface area of the Li electrode. Therefore, non-uniform dissolution/deposition reaction and resultant Li dendrite deposit are expected at lower temperatures even in LiNO3/G4 due to the reaction resistance of dissolution/deposition of Li and poor supply of Li+ ions to the Li electrode.On the day of the presentation, the effect of LiNO3 will be discussed in more detail by comparing the results of simultaneous changes in temperature and current densities.This study was supported by JST Projest ALCA-SPRING (JPMJAL1301) and NIMS Joint Research Hub Program, Japan.[1] M. Saito, T. Fujinami et al., J. Electrochem. Soc., 164, A2872 (2017).[2] M. Saito, T. Fujinami et al., J. Electrochem. Soc., 168, 010520 (2021). Figure 1