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Preparation Coffee Bean Recycled Supercapacitor Materials and Its Electrochemical Performance

Coffee generates a large amount of residues owing to enormous everyday consumptions in worldwide. In this study, coffee bean wastes (CBW) are carbonized at different temperature of 750, 800, and 850℃ under N2 atmosphere to synthesize an active material for supercapacitor. Among various temperature control, CBW-850 exhibits the highest specific capacitance of 65 F/g at current density of 1.0 A/g. In addition, MnO2 materials are deposited onto the as-synthesized CBW-850 to attain MnO2-coated CBW-850 (CBW@MnO2) for further increment of electrochemical performance by adding hybrid capacitance. Finally, asymmetric supercapacitor device (CBW-850//CBW-850@MnO2) is assembled with employing CBW-850 and CBW@MnO2 as positive and negative electrodes. The resulting asymmetric supercapacitor device is able to enlighten the red LED, indicating the operating voltage window of 2.0V. To sum up, coffee bean wastes are successfully converted into a active material for supercapacitor, showing the possibility for facile recycling method of wastes into electrochemical-related materials.