High-mass loaded MnOOH/MnO2/CC electrode with novel 3D structures for high-performance supercapacitors

Manganese (Mn)-based oxides have attracted much interest as a promising electrode material for high-energy-density supercapacitors, however the electrochemical performance deteriorate significantly with increasing mass loading due to their intermediate electronic and ionic conductivities, which severely limits their practical capacitance. Here, we successfully prepared a MnOOH/MnO 2 /CC composite electrode with 3D structure consisting of MnO 2 nanorods and MnOOH nanosheets grown on carbon cloth (CC) by a simple hydrothermal method, which achieved an ultra-high mass loading of 17.45 mg cm −2 but without sacrificing electrochemical performance. The synthesized composite electrode under optimized conditions can work stably under a wide voltage window of 1.2 V and shows a high areal capacity of 1.444mAh cm −2 (or a areal capacitance of 4.331 F cm −2 ) at a current density of 1 mA cm −2 , also with excellent cycling performance (88.5 % capacitance retention after 10,000 cycles). The optimized ASC exhibits a wide voltage window of 2.4 V, a remarkable energy density of 0.751 mWh cm −2 at a power density of 2.881 mW cm −2 . The MnOOH/MnO 2 /CC composite electrode show great potential for future energy storage applications. • A novel three-dimensional structured MnOOH/MnO₂/CC electrode with a high loading capacity of 17.45 mg cm⁻² was prepared. • The optimized sample exhibits a superior capacitance of 1.444mAh cm -2 at 1 mA cm -2 . • The asymmetric supercapacitor delivers a wide voltage of 2.4 V and a desirable energy density of 2.881 mW cm -2 .