A high energy density flexible symmetric supercapacitor based on Al-doped MnO2 nanosheets @ carbon cloth electrode materials

The drawback of traditional capacitors with low energy density forces people to develop high-performance supercapacitor materials. Herein, the Al-doped MnO2 @ carbon cloth is selected as the ideal electrode material. A typical hydrothermal reaction can be used to synthesize Al-doped MnO2 @ carbon cloth at 150 °C for 4 h. Its operating window can be successfully expanded from 0–0.8 to 0–1.2 V, and the areal-specific capacitance reaches 1043 mF cm−2, keeping 91.1% of the original after cycling 5000 times at a current density of 20 mA cm−2. Using the electrode materials designed above, the flexible symmetrical supercapacitor is successfully assembled. This device shows a greater operating window of 0–2.3 V, a superior large areal-specific capacitance of 521.91 mF cm−2, and the energy density remarkably reaches 4.72 mWh cm−3. After 100 bending cycles, there is also basically no loss in performance. This study highlights the promising prospects of the improvement of MnO2 @ CC materials.