Nanostructured materials for energy storage

Traditional electrode materials for lithium-ion storage cells are based on materials which have both mixed electron and ion transport (for Li+). They are typically crystalline layered structures such as metal oxides that have high redox potentials, and act as positive electrodes; and graphitic carbons capable of reversible uptake of Li at low potentials which act as negative electrodes. Recently, however, nanostructured solid state materials, which are comprised of two or more compositional or structural phases, have been considered. This new area has been particularly exploited in the area of negative electrode design, where the intimate mix of components at the nanoscale permits and enhances Li reversibility. It also include cathode materials where materials that function on the basis of intergrowth structures (internal composites) have been found to be beneficial; and insulating materials where the limitations to electron transport must be overcome by judicious design of nanostructured composites. The research trends and future prospects are discussed.