High-performance supercapacitor of manganese oxide/reduced graphene oxide nanocomposite coated on flexible carbon fiber paper

Although supercapacitors have higher power density than batteries, they are still limited by low energy density and low capacity retention. Here we report a high-performance supercapacitor electrode of manganese oxide/reduced graphene oxide nanocomposite coated on flexible carbon fiber paper (MnO2–rGO/CFP). MnO2–rGO nanocomposite was produced using a colloidal mixing of rGO nanosheets and 1.8 ± 0.2 nm MnO2 nanoparticles. MnO2–rGO nanocomposite was coated on CFP using a spray-coating technique. MnO2–rGO/CFP exhibited ultrahigh specific capacitance and stability. The specific capacitance of MnO2–rGO/CFP determined by a galvanostatic charge–discharge method at 0.1 A g−1 is about 393 F g−1, which is 1.6-, 2.2-, 2.5-, and 7.4-fold higher than those of MnO2–GO/CFP, MnO2/CFP, rGO/CFP, and GO/CFP, respectively. The capacity retention of MnO2–rGO/CFP is over 98.5% of the original capacitance after 2000 cycles. This electrode has comparatively 6%, 11%, 13%, and 18% higher stability than MnO2–GO/CFP, MnO2/CFP, rGO/CFP, and GO/CFP, respectively. It is believed that the ultrahigh performance of MnO2–rGO/CFP is possibly due to high conductivity of rGO, high active surface area of tiny MnO2, and high porosity between each MnO2–rGO nanosheet coated on porous CFP. An as-fabricated all-solid-state prototype MnO2–rGO/CFP supercapacitor (2 × 14 cm) can spin up a 3 V motor for about 6 min.