First-Principles Study on Alkali Metal-Graphite Intercalation Compounds

INTRODUCATION Li-ion batteries have been extensively examined and are key technology in modern society. However, it is said that the lithium resources are not sufficient and the cost of raw material has the possibility of rising in the future. Recently, the Na-ion batteries are actively researched because it, where lithium as the current carrier is substituted with sodium which is far more abundant than lithium, is expected to alternative to Li-ion batteries due to its potential cost advantages. However, the performance of Na-ion batteries is lower than that of Liion batteries now. So, it is expected to develop the high performance active materials for Na-ion batteries. To achieve this purpose we analyze the behavior of the sodium in the active materials. In this study, we focus on the graphite, which is good anode active material for Liion battery, because it is interestingly reported that the sodium hardly intercalates into the graphite though the lithium intercalate into it [1]. To clear this difference, we carried out first-principles calculations of alkali (Li, Na, K) metal-graphite intercalation compounds (AM-GICs).