Graphene-hollow-cubes with network-faces assembled a 3D micro-structured transparent and free-standing film for high performance supercapacitorsElectronic supplementary information (ESI) available: Calculation methods, some morphological characterizations and a list of the specific volumetric capacitances from a previous study are available. See DOI: 10.1039/c7ta03935b

Transparent all-solid-state supercapacitors are advanced power supply devices for multifunctional high-end electronics. However, the areal capacitance is seriously limited due to the low mass loading, as high transmittance usually corresponds to ultra-small electrode thickness, which hinders practical applications. Here, we develop an effective three-dimensional (3D) architecture using plasma-etched micro-structured NaCl as the template. The film is assembled by graphene hollow-cube building units, and the faces of the cubes are graphene network microstructures. The graphene-network-face hollow-cube units (GNHC) fully exploit the large surface area of graphene, ensure the transparency of the film and reduce junction contact resistance between the graphene sheets. As expected, the film exhibits improved areal capacitance (5.48 mF cm −2 ), high volumetric energy (657.2 μW h cm −3 ), and power densities (954.3 mW cm −3 ). Generally, GNHC based films will be promising energy storage materials and very suitable supports or templates for construction of graphene-based composites. A kind of 3D micro-structured transparent and free-standing film assembled by graphene-hollow-cubes with network-faces was developed using a micro-structured NaCl template.