A Low-Cost and High-Efficiency Electrothermal Composite Film Composed of Hybrid Conductivity Fillers and Polymer Blends Matrix for High-Performance Plate Heater

Owing to easy processability, ultralight weight, and low cost, carbon- and polymer-based composite materials are among emerging and promising electrothermal materials for high-performance flexible electric heaters. In this work, a sandwich-like structured electrothermal film composed of hybrid conductive fillers [Super-P (SP) and graphite], polymer blends matrix [thermoplastic polyurethane (TPU) and polyethersulfone (PES)], and alumina oxide (Al₂O₃) as a non-conductive filler has been fabricated by a facile slurry coating method. Hybrid conductive fillers of graphite and SP particles have a uniform spatial distribution in a TPU/PES polymer matrix, which construct a highly stable and continuous conductive network with a low percolation threshold of conductive filler content (14.8 wt.%) that allows electrothermal films to operate at a low applied dc voltage. As for the electrothermal film with 15 wt.% hybrid conductive fillers (SP/G-15 sample), it exhibits a superior response feature, high electrothermal conversion efficiency, stable structural stability and remarkable electrothermal reproducibility. More impressively, SP/G-15 composite electrothermal film as an integrated electric heater for heating water demonstrates a high potential in practical application scenarios.