We developed a facile electrochemical charge−discharge method to synthesize single-crystalline Cu nanoparticles with different morphologies by using a Li-driven electrochemical reduction process. Three-dimensional reticular Li2O/Cu2O composite thin films were fabricated on both Ni foam substrates and Cu foil substrates using the electrostatic spray deposition (ESD) technique. Cu nanospheres (on Ni foam substrate) and pyramid-like Cu particles (on Cu foil substrate) can be successfully produced with a high yield by fully discharging the assembly of three-dimensional reticular Li2O−Cu2O /Li electrochemical cells. It was demonstrated that the shape and size of copper nanoparticles could be controlled systematically by adjusting cycle numbers and the electrode substrate materials. In addition, a mechanistic consideration of the size control and shape formation is briefly discussed.