In this dissertation, nanostructured materials are examined for electrochemical energy storage devices with high energy and power densities. While previous research on nanostructured materials for energy storage has mostly focused on the effects of reduced dimensionality on diffusion distances, the research presented here demonstrates how nanostructuring can lead to new charge storage mechanisms. The first part of the dissertation describes the low-potential reactivity of V₂O₅ aerogels and how nanostructuring leads to significantly improved reversibility of the charge storage process. The second part details the rapid kinetic response of T-Nb₂O₅ and in addition, how the combination of nanostructure and appropriate crystalline structure leads to a mechanism called intercalation pseudocapacitance. The third part examines how a 2D nanosheet morphology changes both the redox potentials and kinetics of lithium ion storage in TiO₂. These investigations underscore how reducing a material's dimensions and morphology leads to unique electrochemical behavior beyond simple decreasing of diffusion distances, and how such structures could lead to ultimately higher energy and power density electrochemical energy storage devices.