RESUMEN
The design of flexible wearable electronic devices that can shield electromagnetic waves and work in all weather conditions remains a challenge. We present in this work a low-cost technology to prepare an ultra-thin carbon fabric-graphene (CFG) composite film with outstanding electromagnetic interference shielding effectiveness (EMI SE) and electro-photo-thermal effect. The compatibility between flexible carbon fabric skeleton and brittle pure graphene matrix empowers this CFG film with adequate flexibility. The reticular fibers and porous structures play a vital role in multiple scattering and absorption of electromagnetic waves. In the frequency range of 30-1500 MHz, the CFG film can achieve a significantly high EMI SE of about 46 dB at tiny thickness (0.182 mm) and density (1.4 g cm-3) predominantly by absorption. At low safe voltages or only in sunlight, the film can self-heat to its saturation value rapidly in 40 s. Once the electricity or light supply is stopped, it can quickly dissipate heat in tens of seconds. A combination of the EMI SE and the prominent electro-photo-thermal effect further enables such a remarkable EMI shielding film to have more potential applications for communication devices in extreme zones.
RESUMEN
In the 5G era, for portable electronics to operate at high performance and low power levels, the incorporation of superior electromagnetic interference (EMI) shielding materials within the packages is of critical importance. A desirable wearable EMI shielding material is one that is lightweight, structurally flexible, air-permeable, and able to self-clean. To this end, a bioinspired electroless silver plating strategy and a one-step electrodeposition method are utilized to prepare an EMI shielding fabric (CEF-NF/PDA/Ag/50-30) that possesses these desirable properties. Porous CEF-NF mats with a spatially distributed silver coating create efficient pathways for electron movement and enable a remarkable conductivity of 370 S mm-1. When tested within a frequency range of 8.2-12.4 GHz, this highly conductive fabric not only achieves an EMI shielding effectiveness (EMI SE of 101.27 dB at 5028 dB cm2 g-1) comparable to a very thin and light metal but also retains the unique properties of fabrics-being light, structurally flexible, and breathable. In addition, it exhibits a high contact angle (CA) of 156.4° with reversible surface wettability. After having been subjected to 1000 cycles of bending, the performance of the fabric only decreases minimally. This strategy potentially provides a novel way to design and manufacture an easily integrated EMI shielding fabric for flexible wearable devices.
RESUMEN
Highly conductive carbon-based fibrous composites have become one of the most sought-after components in the field of electromagnetic interference (EMI) shielding due to their excellent comprehensive performance. In this work, a flexible nonwoven fabric consisting of carbon fibers (CFs) and polypropylene/polyethylene (PP/PE) core/sheath bicomponent fibers (ESFs), known as CEF-NF, is introduced into the graphene (GE)/poly(vinylidene fluoride) (PVDF) nanocomposite obtained by a solution casting method to fabricate a CEF-NF/GE/PVDF film. Disparate microstructures can be clearly observed in CEF-NF/GE/PVDF films with different graphene contents. Thanks to an internal porous network structure formed when the graphene content is high, this film exhibits better electrical conductivity. In the frequency range of 30-1500 MHz, this film can achieve a significantly high EMI shielding effectiveness (EMI-SE) value of about 48.5 dB at tiny thickness and density (1731.40 dB cm2 g-1), which are far better than many competitive materials. Moreover, this film exhibits adequate tensile strength and excellent flexibility, as the film's structural form can be retained even after multiple folding processes. In addition, by combining two-dimensional (2D) graphene and one-dimensional (1D) CF, the CEF-NF/GE/PVDF film achieves a remarkable in-plane thermal conductivity of 25.702 W m-1 K-1, making it an exceptional heat conductor. In summary, our results demonstrate that CEF-NF/GE/PVDF film is an excellent EMI shielding material that is light weight, highly flexible, and mechanically robust with outstanding thermal conductivity, which positions it superbly for applications in next-generation commercial portable electronics.