Wood-Derived High-Mass-Loading MnO Composite Carbon Electrode Enabling High Energy Density and High-Rate Supercapacitor.

The simple design of a high-energy-density device with high-mass-loading electrode has attracted much attention but is challenging. Manganese oxide (MnO ) with its low cost and excellent electrochemical performance shows high potential for practical application in this regard. Hence, the high-mass-loading of the MnO electrode with wood-derived carbon (WC) as the current collector is reported through a convenient hydrothermal reaction for high-energy-density devices. Benefiting from the high-mass-loading of the MnO electrode (WC@MnO -20, ≈14.1 mg cm ) and abundant active sites on the surface of the WC hierarchically porous structure, the WC@MnO -20 electrode shows remarkable high-rate performance of areal/specific capacitance ≈1.56 F cm /45 F g , compared to the WC electrode even at the high density of 20 mA cm . Furthermore, the obtained symmetric supercapacitor exhibits high areal/specific capacitances of 3.62 F cm and 87 F g at 1.0 mA cm and high energy densities of 0.502 mWh cm /12.2 Wh kg with capacitance retention of 75.2% after 10 000 long-term cycles at 20 mA cm . This result sheds light on a feasible design strategy for high-energy-density supercapacitors with the appropriate mass loading of active materials and low-tortuosity structural design while also encouraging further investigation into electrochemical storage.