$Li_4Ti_5O_{12}$ is prepared through a solid-state reaction between $Li_2CO_3$ and anatase $TiO_2$ for applications in lithium-ion batteries. The rate capability is measured and the electrode polarization is analyzed through the galvanostatic intermittent titration technique (GITT). The rate characteristics and electrode polarization are highly sensitive to the amount of carbon loading. Polarization of the $Li_4Ti_5O_{12}$ electrode continuously increases as the reaction proceeds in both the charge and discharge processes. This relation indicates that both electron conduction and lithium diffusion are significant factors in the polarization of the electrode. The transition metal (Cu, Ni, Fe) ion added during the synthesis of $Li_4Ti_5O_{12}$ for improving the electrical conductivity also greatly enhances the rate capability.