Manganese oxide/nitrogen-doped carbon aerogels from cellulose nanofibrils for high-performance supercapacitor electrodes

High-performance energy storage devices are in increasing demand for the rapid development of social economy, among which supercapacitors stand out due to their high power density and long cycle life. Here, carbonized cellulose nanofibrils were used to form porous carbon aerogels. And nitrogen from urea was doped in the carbon aerogels to enhance the chemisorption ability and wettability of the surface of carbon materials. Afterwards, manganese oxide/nitrogen-doped carbon aerogels were fabricated through a simple hydrothermal reaction. The composites with a 1:40 mass ratio of carbon aerogels: urea (40-NCMn) showed a maximum specific capacitance of 275.5 F g −1 at 1 A g −1 and an acceptable rate performance of 65.4% when the current density increased 10 times. Using 40-NCMn for positive electrode and activated carbon (AC) for negative electrode, an asymmetric supercapacitor was assembled. It delivered a maximum energy density of 23.3 W h kg −1 and a power density of 600 W kg −1 at 0.5 A g −1 . After 3000 cycles at 5 A g −1 , it could retain 99.2% of the initial capacitance, implying the manganese oxide/nitrogen-doped carbon aerogel a promising material for supercapacitor electrodes. • TEMPO-oxidized cellulose nanofibrils were used for constructing carbon aerogels with rich pore structure. • The optimized carbon aerogels showed a maximum specific capacitance of 275.5 F g −1 and an rate performance of 65.4%. • The obtained asymmetric supercapacitor delivered a maximum energy density of 23.3 W h kg −1 . • The assembled asymmetric supercapacitors could lighten a green light-emitting diode.