Cellulose-Based Conductive Films with Superior Joule Heating Performance, Electromagnetic Shielding Efficiency, and High Stability by in Situ Welding to Construct a Segregated MWCNT Conductive Network

Developing eco-friendly, robust, and multifunctional conductive polymer composites is highly desirable for using as flexible wearable electric elements and meeting the requirements of a sustainable society. Herein, we construct multifunctional cellulose/MWCNT composite films with a superhigh Joule heating performance, outstanding electromagnetic interference (EMI)-shielding efficiency, high electrical conductivity, good mechanical properties, excellent thermostability, and adequate water resistance. The resultant cellulose/MWCNT composite films possess a special segregated MWCNT conductive network structure by using a simple paper-making process and a subsequent in situ welding process with an ionic liquid as the solvent of cellulose. Their EMI-shielding effectiveness reaches 49.2 dB with a thickness of 0.3 mm, their electrical conductivity reaches 1901 S/m, their tensile strength reaches 110 MPa, and their initial decomposition temperature is higher than 300 °C. In particular, they show a superhigh Joule heating performance at a low driving voltage. When the driving voltage is as low as 2 V, the temperature of the cellulose/MWCNT composite rapidly increases to 166 °C, which is dramatically higher than those of the previously reported polymer composite heaters. Cellulose/MWCNT composite films with such an outstanding combination performance can be used as multifunctional flexible conductive elements for the fabrication of a deicing device, a portable heat sealer, and an EMI-shielding device.