(i) The use of thicker electrodes which maximizes material loading with respect to the entire device weight/volume. Therefore, development of material architectures that can provide high energy densities for the thicker electrodes is very important. This is one of the principal motivations for developing 3D composite electrode architectures that would address issues of impeded ion transport and decreased conductivity for thicker electrodes. Some initial examples demonstrating thicker structures include oxide nanoparticles supported on 3D graphene networks22, carbon nanotubes23 and graphene layers2425 aligned normally to the separator surface.