Design of NiCo2O4 nanoparticles in-situ grown on lignin-derived porous carbon and MWCNTS composites for supercapacitors

Dendritic NiCo2O4/MWCNT-x/PC-y composite materials based on lignin derived-porous carbon (PC) as skeleton and MWCNT as stem, NiCo2O4 as fruit were successfully synthesized by pyrolysis and subsequent solvothermal method. Lignin derived-PC provides high surface area and electrical conductivity, and also alleviates the agglomeration of the materials. MWCNT provides channels for faster charge transfer and an excellent microenvironment for the Faradic reaction of NiCo2O4, while NiCo2O4 endows an ultrahigh specific capacitance, so that their synergies enhance intrinsic activity. Among all prepared materials, NiCo2O4/MWCNT-0.25/PC-0.48 exhibited a higher specific capacitance (485.7 F g(-1)), which was greatly improved as compared with 202.5 F g(-1) of NiCo2O4. Electrochemical impedance spectroscopy test showed that NiCo2O4/MWCNT-0.25/PC-0.48 exhibited the lowest Rct value (similar to 1.0 O), and its capacitance retention rate was about 78 % after 5000 cycles of galvanostatic charging and discharging at 8.0 A g(-1). The superior electrochemical performance of the composites as supercapacitor material is attributed to the properties of the pristine components. The results demonstrate that NiCo2O4/MWCNT-0.25/PC-0.48 is a promising electrode material for supercapacitors.