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There is an increasing interest in the development of rechargeable batteries suitable for use in both hybrid electric vehicles and energy storage systems that require higher charge & discharge rates, bigger battery sizes and increased safety of the batteries. Spinel-type lithium titanium oxide (Li4Ti5O12) as a potential anode for lithium ion batteries has many advantages. It is a zero-strain materials and it experiences no structural change during the charge/discharge precess. Thus, it has long cycle life due to its structural integrity. It also offers a stable operation voltage of approximately 1.55 V versus Li + /Li, above the reduction potential of most organic electrolyte. In this study, Ru added Li4Ti5O12 composites were synthesized by solid state process. The characteristics of active material were investigated with TGA-DTA, XRD, SEM and charge/discharge test. The capacity was reduced when Ru was added, however, the polarization decreased. The capacity rate of Li4Ti5O12 with Ru (3%, 4%) addition was reduced during the charge/discharge precess with 10 C-rate as a high current density.

The electorchemical properties of Li4Ti5O12 added with Cr was tested. The addition or substitution of atoms to Li4Ti5O12 are expected to modify the crystal structure, and therefore to change the electrochemical performances of Li4Ti5O12. After the spinel structure Li4Ti5�xCrxO12 (x = 0~0.2) were obtained via sol-gel method, the gel was heated in a muffle furnace at 800~ 850 o C for 12 h in air. The physical properties of the samples were characterized by TG-DTA, XRD, SEM, FT-IR, and the electrochemical properties were tested with battery cycler at 0.01~2.0 V range. The Li4Ti5O12 exhibited 169.9 mAh/g at 1C and capacity recovery was 97.5% of the initial capacity at 0.1C. Li4Ti4.9Cr0.1O12 (Cr 1% added) showed best performance of 193.8 mAh/g at 1C and the capacity recovery was increased to 98.8% of the initial capacity at 0.1C.