Lignin-derived ECNF mats were surface-decorated with MnO<sub>2sub> nanowhiskers.
ECNF/MnO<sub>2sub> mats were explored as freestanding binder-free supercapacitor electrodes.
ECNF/MnO<sub>2sub> (1:1) mat/electrode exhibited the highest electrochemical performance.
An approach for making high-performance supercapacitor electrodes was demonstrated.