The capability of synthesizing materials with nanometer size and shape control has enabled exciting opportunities to engineer materials for controlling and understanding electronic, photonic, mechanical and ionic processes, which are important for applications such as energy conversion and storage devices. In this talk I will show two examples on how we design nanoscale materials towards high performance photovoltacis and energy storage devices. In the first example, nanocone- and nanodome-shaped substrates are designed for efficient photon management and charge carrier separation, which result in significant improvement of solar cell power efficiency compared to the flat film devices. Second, nanowires are exploited to maximize efficiency of simultaneous electron and ionic insertion with facile strain relaxation, which enable novel ultrahigh charge storage capacity materials towards next generation of high energy density batteries.