Pencil-drawing assembly to prepare graphite/MWNT hybrids for high performance integrated paper supercapacitors

As a promising solution for the next generation of flexible and disposable electronics, paper-based devices are being studied intensively. However, as one of the cores of paper-based devices, many reported supercapacitors (SCs) suffer from disadvantages such as cumbersome fabrication, complicated packaging, low power density etc. Here we demonstrate a facile and scalable method to fabricate paper-based SCs by an improved pencil drawing strategy. The multi-walled carbon nanotubes are directly assembled onto pencil graphite flakes to form controllable graphite/MWNT frameworks, which act as high-performance electrodes. These SCs can deliver a power density of up to 15.1 W cm^-3 and cycle at a scan rate of up to 150 V s^-1, which are among the highest values achieved for any paper-based SCs. To demonstrate their applicable power/energy densities, the SCs are applied in series to drive LED and wireless sensor systems based on Bluetooth technology.