The positive electrode (cathode) material Li~0~.~7~5Na~0~.~2~5MnO~1~. ~9~2I~0~.~0~8 for lithium-ion secondary batteries was synthesized using LiOH as the Li source, MnO~2 as the Mn source, NaI as an additive, and acetonitrile as non-aqueous solvent at room temperature under atmospheric pressure, and was characterized by XRD, BET and TEM as well as electrochemical testing. The results have demonstrated that Li~0~.~7~5Na~0~.~2~5MnO~1~.~9~2I~0~.~0~8 as-synthesized compound is amorphous ultrafine powder with the mean diameter being approximately 45～60nm. Li~0~.~7~5Na~0~.~2~5MnO~1~.~9~2I~0~.~0~8 has a large specific surface area (about 35～48m^2/g). After dried at 260 ℃ in vacuum, the sample was transformed into nano-sized crystals, The results of electrochemical studies have revealed that when this dried compound as cathode material and the lithium metal was used as counter-electrode material to compose of a lithium cell, and charged/discharged with a stable current under the conditions of 1.5～ 4.3V range and 0.353mA/cm^2, the first charge and discharge specific capacity was more than 280(mA·h)/g, and the discharge/charge ratio was more than 95%. After 20 cycles, the charge and discharge specific capacity was also more than 260(mA·h)/g. Therefore, this compound is a cathode material for lithium-ion secondary batteries with remarkable application prospects.

Key words: LITHIUM ION, BATTERIES, LITHIUM HYDROXIDE, MANGANESE DIOXIDE, X-RAY DIFFRACTION ANALYSIS, TRANSMISSION ELECTRON MICROSCOPY