Electrolyte contribution to the multifunctional response of cellulose carbon nanotube fibers

Flexible wearable multifunctional devices such as cellulose loaded with electroactive components are in the focus of modern research for electrochemical energy storage, sensors and actuators. In this report, the multifunctional response of cellulose with 50 wt% MWCNT formed into Cell-CNT composite fibers is demonstrated. The effect of (aqueous) electrolyte choice on the electro-mechanical response of Cell-CNT was studied. Aqueous electrolytes such as tetramethylammonium chloride (TMACl), sodium perchlorate (NaClO4), and 1-ethyl-2,3-dimethylimidazolium trifluoromethanesulfonate (EDMITF) were considered, with the resulting stress and strain decreasing in the order Cl− > ClO4− > TF−, matching the order of the size of the ions. Upon negative charging, the cations of the electrolytes showed electromechanical response in the order: TMA+ > EDMI+ > Na+, where the solvation strength of the cations had stronger influence than their size without solvation shell. The highest specific capacitance was shown by TMACl in the range of 74 mF cm−2 upon positive charging, with also the best retention of capacitance of 86% in long-term measurements. Chronopotentiometric measurements of Cell-CNT fibers where conducted to evaluate if the composites can also act as sensors for different electrolytes. The Cell-CNT fibers were characterized with scanning electron microscopy, energy dispersive X-ray, FTIR and Raman spectroscopy.