Aqueous Manganese Dioxide Ink for Paper-Based Capacitive Energy Storage Devices.

We report a simple approach based on a chemical reduction method to synthesize aqueous inorganic ink comprised of hexagonal MnO2 nanosheets. The MnO2 ink exhibits long-term stability and continuous thin films can be formed on various substrates without using any binder. To obtain a flexible electrode for capacitive energy storage, the MnO2 ink was printed onto commercially available A4 paper pretreated with multiwalled carbon nanotubes. The electrode exhibited a maximum specific capacitance of 1035 F g−1 (91.7 mF cm−2). Paper-based symmetric and asymmetric capacitors were assembled, which gave a maximum specific energy density of 25.3 Wh kg−1 and a power density of 81 kW kg−1. The device could maintain a 98.9 % capacitance retention over 10 000 cycles at 4 A g−1. The MnO2 ink could be a versatile candidate for large-scale production of flexible and printable electronic devices for energy storage and conversion. [ABSTRACT FROM AUTHOR]