Chain-ring covalently interconnected cellulose nanofiber/MWCNT aerogel for supercapacitors and sensors

Bending multi-walled carbon nanotubes (MWCNTs) into rings and structuring them into aerogels is difficult. In this study, cellulose nanofiber (CNF)-MWCNT composite fibers with chain-ring structures were prepared by covalently interconnecting carboxylated CNF and aminated MWCNT by dehydration condensation, solving the problems of the formation of MWCNT aerogels and their phase separation during the compounding process and providing CNF-based aerogels with electrical conductivity. The covalently interconnected aerogels (CAs) had hierarchical porous structures with mechanical resilience and chain-ring fibers, which drove the CNF and MWCNT to form a continuous homogeneous network resulting in a high compression resistance of 269.02 kPa. The CA-based flexible all-solid-state supercapacitor had a quality specific capacitance of 114.8 F g^-1, a capacitance retention rate of 94.78% and a Coulomb efficiency of 100%. The CA-based flexible sensor can sense different pressures with a stable response for 1000 cycles. This first study of pulling and bending MWCNT through CNF is expected to inspire more applications of MWCNTs in the fields of flexible supercapacitors and sensors.