-A series of Mn compound were prepared by seed-assisted method. The seed used in this reaction was manufactured by calcination of MnCO 3 at various temperatures and effects of the calcination temperature on seed-assisted reaction were investigated. With increase of the calcination temperature, CMD (γ-MnO 2 ) was recovered after seedassisted reactions . LMO used as cathode active material in the Li-ion batteries were synthesized from Mn source obtained in the seed-assisted reaction and the electrochemical properties (rate capability, cycle life performance and specific capacity) of the LMO were investigated. The LMO synthesized from the CMD which is obtained by the reaction with seed prepared by calcination of MnCO 3 more than 350 o C shown good electrochemical properties.

Al doped LiMn 2 O 4 (LiMn 2 O 4 :Al) synthesized by several Al doping process and Solid State method. The Al contents in Mn 1-x Al x O 2 for LiMn 2 O 4 :Al were analyzed 1.7 wt% by EDS. The LiMn 2 O 4 :Al confirmed cubic spinel structure and approximately 5 µm particles regardless of three kinds of doping process by solid state method. In the result of electrochemical performances, initial discharge capacity had 115 mAh/g in case of LiMn 2 O 4 and 111 mAh/g of LiMn 2 O 4 :Al after 100th cycle at room temperature. But the capacity retention results showed that LiMn 2 O 4 and LiMn 2 O 4 :Al were 44% and 69% respectively in the 100th cycle at 60 o C. Therefore we are confirmed that LiMn 2 O 4 :Al increased the capacity retention about 25% than LiMn 2 O 4 , thus the effect of Al dopping on LiMn 2 O 4 capacity retention.