Binder-free activated graphene compact films for all-solid-state micro-supercapacitors with high areal and volumetric capacitances

Micro-supercapacitors (MSCs) hold great promise as highly competitive miniaturized power sources satisfying the increased demand in microelectronics; however, simultaneously achieving high areal and volumetric capacitances is still a great challenge. Here we demonstrated the designed construction of binder-free, electrically conductive, nanoporous activated graphene (AG) compact films for highperformance MSCs. The binder-free AG films are fabricated by alternating deposition of electrochemically exfoliated graphene (EG) and nanoporous AG with a high specific surface area of 2920 m(2)/g, and then dry transferring onto the target substrates with a high-pressure mechanical densification process. Remarkably, the resulting compressed AG films showed uniform morphology in lateral dimensions, high conductivity (60 S/cm), nanoporous feature ( < 10 nm), and high packing density (0.8 g/cm(3)). The all-solid-state MSCs (AG-MSCs) based on these AG films simultaneously delivered an unprecedented areal capacitance of 89.5 mF/cm(2) and volumetric capacitance of 147 F/cm(3) for MSCs at 10 mV/s. Moreover, the fabricated AG-MSCs could be operated at a large scan rate of 10,000 mV/s, and showed outstanding cycling stability (capacitance retention of > 99.6% after 10,000 cycles). Our results suggested that AG-MSCs are competitive for prospective applications of miniaturized energy storage devices. (C) 2015 Elsevier B.V. All rights reserved.