There have been exciting developments in new electrode materials for lithium ion batteries in the past decade. Nanostructured materials have emerged as highly suitable candidates, including Si anode and LiFePO4 cathode materials, and are starting to be used in the marketplace. Promising electrochemical properties including excellent kinetics and cycling stability have driven research interest in nanomaterials. This review highlights the major roles of nanosize in lithium reactive nanomaterials for Li ion batteries, with the aim of providing nanomaterial scientists with a better understanding of electrochemical concepts that can be exploited for tailored design of electrode materials. (C) 2010 Elsevier Ltd. All rights reserved.