▎ 摘　　要

Polymer nanocomposites with excellent electromagnetic interference (EMI) shielding and thermal conductivity (TC) are urgently needed to solve the increasingly serious electromagnetic pollution and heat accumulation in devices. Herein, a distinct strategy was proposed to improve the dispersity of graphene nanoplatelets (GNPs) and integrate cellulose nanofiber (CNF), graphene nanoplatelets (GNPs), and MXene into a layered structure. The presence of MXene can improve the dispersity of GNPs, and the presence of GNPs can protect MXene from oxidation. By combining the excellent electrical conductivity of MXene and the high thermal conductivity of GNPs, the CNF/ GNPs/MXene composite films exhibit excellent EMI shielding performance and high in-plane thermal conductivity. The electromagnetic shielding property of the CNF/GNPs/MXene composite films reaches 33.74 dB and the in-plane TC is 8.55 W/(m.K) when the total filler content is 50 wt % while the thickness of the composite film is only 38.5 mu m. In addition, the mechanical properties of the composite membrane can meet general requirements. Therefore, these ultrathin CNF/GNPs/MXene composite films show great application potential as effective EMI shielding and thermal management materials.