The role of intercalation/insertion reactions in battery electrodes was first recognized just over 25 years ago. From the first prototypical titanium disulfide cells, the technology has more recently been commercialized by Sony in the Li-ion cell using a cobalt oxide insertion cathode and a carbon insertion anode. These cells have proved themselves highly successful in the field in small devices, such as cellular phones and portable computers. However, their energy density is no higher than the titanium sulfide system and they are too expensive for large-scale application. Therefore, the search is on for lower cost cathodes that have at least double the energy density of the present systems. The research trends and future prospects are discussed.