Development of non-flammable lithium secondary battery with room-temperature ionic liquid electrolyte: Performance of electroplated Al film negative electrode

The negative electrode performance of the electroplated Al film electrode in the LiCl saturated AlCl3–1-ethyl-3-methylimizadolium chloride (EMIC) + SOCl2 melt as the electrolyte for use in non-flammable lithium secondary batteries was evaluated. In the cyclic voltammogram of the electroplated Al film electrode in the melt, the oxidation and reduction waves corresponding to the electrochemical insertion/extraction reactions of the Li+ ion were observed at 0–0.80 V vs. Li+/Li, which suggested that the electroplated Al film electrode operated well in the electrolyte. The almost flat potential profiles at about 0.40 V vs. Li+/Li on discharging were shown. The discharge capacity and charge–discharge efficiency was 236 mAh g−1 and 79.2% for the 1st cycle and it maintained 232 mAh g−1 and 77.9% after the 10th cycle. In addition, the initial charge–discharge efficiencies of the electroplated Al film electrode were higher than that of carbon electrodes. The main cathodic polarization reaction was the insertion of Li+ ions, and side reactions hardly occurred due to the decomposition reaction of the melt because the Li content corresponding to the electricity was almost totally inserted into the film after charging.