Abstract: In this paper we report on the impact of nanomaterials on lithium rechargeable battery performances. Nanotubes (single wall carbon nanotube and multi wall carbon nanotube, NiO and WS2), nano-intermetallic alloys (Cu6Sn5, Sn/SnSb and Sn/SnNi), nano-oxides (NiO, CoO, SnO2 and Co3O4), nano-composites (C-LiFePO4, Si-C, Si-MCMB (mesocarbon microbeads), Si-TiC, Si-PPY (polypyrrole) and MWNT(multiwalled nanotubes)/Sn/SnNi), as well as other nanoparticles (TiO2, SiO2, and Al2O3) have been used in lithium rechargeable batteries in our studies. "Free-standing" single wall carbon nanotube (SWNT) papers produced without an), binder and metal substrate shows a capacity slightly lower than that of the conventional electrode. Carbon-coated Si nanocomposites produced by a spray-pyrolysis technique can reversibly store lithium with a high capacity of 1489 mAh/g and a high coulumbic efficiency above 99.5%, even after 20 cycles. Nanosize 10 wt% TiO2 increased the ionic conductivity of PEO-LiClO4 polymer electrolyte by a factor of 2 at room temperature and at elevated temperature.