▎ 摘　　要

Developing the polymer-based thermal interface materials (TIMs) is one of the most promising approaches to address heat accumulation along with the functionalization, integration, and miniaturization of modern electronics, while it is still a great challenge to balance the thermal conductivity and mechanical properties. In this article, Fe ion- anchored graphene (FeG) is successfully fabricated by a facile in situ Fe reduction of graphene oxide (GO) approach, and then cellulose nanofibers (CNFs)/FeG composites are prepared by vacuum-assisted filtration. FeG exhibits excellent dispersion and exfoliation in CNFs/FeG composites, due to the strong interfacial interaction between CNFs and FeG, such as hydrogen bonds and ''Fe-O'' complex binding. Thus, CNFs/FeG composite has the largely improved thermal conductivity up to 30.2 W/mK at FeG content of 50 wt%, which is substantially increased by 1160% in comparison with that of pure CNFs. In addition, the mechanical performances of CNFs/FeG-50 are unexpectedly simultaneously enhanced to 244 MPa for tensile strength, 4.10% for elongation at break, and 9.5 GPa for Young's modulus, outperforming pure CNFs with increase of 137%, 33%, and 121%, respectively. This study provides a significant strategy for the design and construction of high thermal conductivity and high-performance polymeric TIMs in flexible and portable electronics.