A lithium ion battery is disclosed in which the negative electrode material comprises carbon nanostructures having no dimension greater than 2 .mu.m. The battery has a high reversible capacity of the order of 400 mAh/g to 500 mAh/g which can be maintained over a long cycle-life (at least 30 cycles). The carbon nanostructures may be mixed with graphite to improve conductivity. The carbon nanostructues may be synthesized using an AFI template material followed by calcination.