Lithium intercalation compounds confined with carbon nanotubes in nanoporous zeolite crystals were analyzed. A plane-wave pseudopotentials formulation was used to perform the first-principles calculations which shows the presence of several possible sites for lithium to be intercalated. The lithium capacity of the system was found to be as high as 10% by weight, higher than that of graphite intercalation compounds, as indicated by the vapor phase adsorption and electrochemical measurements. The nanotubes-zeolite complex acted as a significant candidate for lithium battery applications because of the enhanced lithium capacity.