(September 23, 2015) The Department of Applied Physics of The Hong Kong Polytechnic University (PolyU) has developed a simple approach to synthesize novel environmentally-friendly manganese dioxide (MnO2) ink by using glucose. The MnO2 ink could be used for the production of light, thin, flexible and high performance energy storage devices via ordinary printing or even home-used printers. The capacity of the MnO2 ink supercapacitor is more than 30 times higher than that of a commercial capacitor of the same weight of active material (e.g. carbon powder), demonstrating the great potential of MnO2 ink in significantly enhancing the performances of energy storage devices, whereas its production cost amounts to less than HK$1.
MnO2 is a kind of environmentally-friendly material and it is degradable. Given the environmental compatibility and high potential capacity of MnO2, it has always been regarded as an ideal candidate for the electrode materials of energy storage devices. The conventional MnO2 electrode preparation methods suffer from high cost, complicated processes and could result in agglomeration of the MnO2 ink during the coating process, leading to the reduction of electrical conductivity. The PolyU research team has developed a simple approach to synthesize aqueous MnO2 ink. Firstly, highly crystalline carbon particles were prepared by microwave hydrothermal method, followed by a morphology transmission mechanism at room temperature. The MnO2 ink can be coated on various substrates, such as conductive paper, plastic and glass. Its thickness and weight can also be controlled for the production of light, thin, transparent and flexible energy storage devices. Substrates coated by MnO2 ink can easily be erased if required, facilitating the fabrication of electronic devices.