▎ 摘　　要

Graphene films promise great application potential in modern electronic devices due to their superior electrical and thermal conductivities. However, the green manufacturing of graphene films is still faced with challenges. Also, graphene films prepared by the oxidation and exfoliation method are expensive and exhibit poor mechanical properties. In this work, the highly conductive graphene-based film with reinforced mechanical strength is fabricated by employing cellulose nanofiber (CNF) to help expandable graphite (EG) exfoliate directly in aqueous solution and poly(ethylene oxide) (PEO) to construct a nacre-like structure. Herein, we succeeded in addressing the issue of the graphene films unsatisfactory cost and mechanical properties by using very cheap EG as the raw material and taking advantage of the synergistic performance of the two-dimensional EG nanoplatelet, one-dimensional CNF, and flexible PEO. When the mass ratio of EG, CNF, and PEO reaches 95:5:3, the graphene-based film displays a relatively high tensile strength (about 63.3 MPa), which shows a 587% increase over that of EG film (9.2 MPa) and is much higher than those of the reported graphene films prepared through physical exfoliation to our knowledge. Moreover, it shows extraordinary electrical conductivity (1226 S cm(-1)), thermal conductivity (302.3 W m(-1) K-1), and electromagnetic interference shielding effectiveness (44 dB with a thickness of 12 mu m). In summary, the manufacturing route of the EG/CNF/PEO composite film is efficient, economical, and promising for commercial applications in the contemporary electronic industry.