高ニッケル三元系材料は商用のLiCoO2正極より高い容量を有するため、EVsで使用するリチウムイオン電池の正極材料の候補として有望である。本論文に、著者は濃厚電解液とフッ素化溶媒を用いた希釈電解液に着目し、高ニッケル三元系LiNi0.8Co0.1Mn0.1O2(NCM811)の充放電サイクル特性を向上させた。電解液中の溶媒化構造の観点から、濃厚電解液の希釈効果がNCM811の充放電特性に及ぼす影響を詳細に検討した。 / Ni-rich ternary materials have higher capacity than the commercial LiCoO2 positive electrode, and therefore they are promising candidates for the positive electrode material of lithium ion batteries for use in EVs. In this thesis, the author focused on highly concentrated electrolytes and their diluted electrolytes with fluorinated solvents to improve the cycling performance of a Ni-rich ternary LiNi0.8Co0.1Mn0.1O2 (NCM811) for practical application. Dilution effects of the concentrated electrolytes on the charge/discharge properties of NCM811 were discussed in detail from the viewpoint of the solvation structure in the electrolyte. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University