Pressure-Induced Self-Interlocked Structures for Expanded Graphite Composite Papers Achieving Prominent EMI Shielding Effectiveness and Outstanding Thermal Conductivities

Abstract

High-performance films via layer-by-layer assembly of twodimensional (2D) materials would provide all possibilities for the development of modern integrated electronics. However, the stacked structure between nanosheets and large-scale fabrication still remain a great challenge. Herein, Fe 3 O 4 /expanded graphite (EG) papers are fabricated via in situ oxidation of ferrocene onto EG nanosheets, followed by a continuous roll-in process. Upon mechanical compaction, the self-interlocked structures driven by close overlapping and hooking of nanosheets in Fe 3 O 4 /EG (FG) composites remarkably facilitate the construction of phonon and electron transmission channels and improve mechanical strength. FG papers exhibit prominent shielding effectiveness (67.1 dB at ∼100 μm) with enhanced absorptivity (∼0.1, surpassing lots of conductive film materials), stemming from the synergistic effect of electrical and magnetic properties. Also, the electromagnetic interference (EMI) shielding performance shows prominent reliability after bending (2000 cycles) and ultrasonic treatment (30 min). The corresponding tensile strength reaches 35.8 MPa; meanwhile, the corresponding in-plane thermal conductivity coefficient is as high as 191.7 W/(m•K), which can rapidly and efficiently accelerate heat dissipation. In particular, FG papers also reveal rapid response, controllable, and highly stable Joule heating performance and present promising prospects in the fields of radiation-proof clothing, flexible heaters, portable wearable devices, and aerospace.

Structural evolution of MXenes and their composites for electromagnetic interference shielding applications

“…Because MXenes have very high conductivities with numerous free electrons on their surfaces, when electromagnetic waves meet MXenes (such as a pristine Ti 3 C 2 T x film), the majority of the waves will be reflected immediately and the reflection loss will be large. The magnitude of the reflection loss on the surface of the shielding material can be described by the simplified form of the following Fresnel equation: 128,129 where η and η 0 represent the impedance of the shielding layer and the air, σ stands for the conductivity of the shielding layer, μ is the magnetic permeability of the shielding layer, and f is the frequency of the incident EM wave. As observed in the formula, the better the material's electrical conductivity, the lower the magnetic permeability, and the greater the SE R .…”

“…Because MXenes have very high conductivities with numerous free electrons on their surfaces, when electromagnetic waves meet MXenes (such as a pristine Ti 3 C 2 T x film), the majority of the waves will be reflected immediately and the reflection loss will be large. The magnitude of the reflection loss on the surface of the shielding material can be described by the simplified form of the following Fresnel equation: 128,129…”

Thermally conductive polymer-based composites: fundamentals, progress and flame retardancy/anti-electromagnetic interference design

“…22a). 219 The self-interlocking structure driven by the tightly overlapping and hook-like nanosheets in Fe 3 O 4 / EG (FG) composites significantly facilitates the construction of phonon and electron transport channels. The corresponding in-plane thermal conductivity is as high as 191.7 W m À1 K À1 , which can accelerate heat dissipation quickly and efficiently (Fig.…”

Flexible Smart Wearable Co@C@Carbon Fabric for Efficient Electromagnetic Shielding, Thermal Therapy, and Human Movement Monitoring

“…Co-PCCF possesses excellent Joule thermal performance due to an excellent conductive network, which is beneficial for alleviating edema and joint pain by thermal therapy. 48 Figure 7a shows the Joule thermal performance of ZIF-67@CF, Co-PCCF-700, Co-PCCF-800, Co-PCCF-900, and Co-PCCF-1000 at different DC voltages. As a comparison, the Joule heating performances of cotton non-woven fabric and PCF at different voltages are shown in Figure S6a.…”