Multifunctional structural composite supercapacitors based on MnO2-nanowhiskers decorated carbon fibers

We report the concept of stiff, strong, and lightweight multifunctional composites that can perform as a structural composite supercapacitor. The self-assembly of Manganese Dioxide (MnO 2 ) nanowhiskers decorated carbon fiber (MO-CF fiber) composites enabled improvement in surface area, electrical conductivity, and a high number of active sites of the carbon fiber electrodes, thereby, exhibiting excellent charge storage capacity for the composite supercapacitors. The MO-CF-integrated composites achieved a specific capacitance of 1.1 F g −1 , which is a 120-fold increase compared with neat carbon fiber–based supercapacitors. Moreover, the composite supercapacitor device showed an energy density of 2.45 W h kg −1 . The fabricated device also achieved a capacitance of 1.71 F g −1 and an energy density of 3.8 Wh kg −1 in a 3 M NaCl solution. With an exceptional increase in its electrochemical properties, the MO-CF-based composite also maintained its mechanical properties, exhibiting an increase in tensile strength up to 123.6 MPa. Additionally, we demonstrated the feasibility of using a MO-CF composite as a structural supercapacitor by illuminating an LED. • MnO 2 -nanowhiskers decorated carbon fiber reinforced composites. • Multifunctional structural supercapacitor device with excellent electrochemical and mechanical properties • A LED is illuminated for more than 20 min to demonstrate the proof of concept.