Ultra-flexible and high-performance electromagnetic wave shielding film based on CNTF/liquid metal composite films

Abstract

A thin, lightweight, and flexible composite of carbon nanotube film (CNTF) with gallium indium tin (GaInSn) liquid metal (LM), denominated as CNTF/GaInSn, was fabricated for electromagnetic interference (EMI) shielding material. Scanning electron microscopy shows that CNTs with an average diameter of 2 nm are randomly distributed. Electric conductivity of CNTF is 396 S cm−1, which is much smaller than that of copper, nickel, GaInSn, etc. The measured EMI shielding efficiency (SE) of a CNTF/GaInSn composite film of sandwich structure (bilayer CNTF and single layer GaInSn) is around 55 dB in an X band (8.2–12.4 GHz), which is higher than that of bilayer CNTFs by 20 dB, indicating that the presence of the embedding GaInSn LM layer greatly improves the EMI SE of CNTF. EMI SE also increases with increasing the number of CNTF layers, but the increased EMI SE by adding the number of the CNTF layer is not comparable to that of by embedding the GaInSn layer between two layers of CNTFs. The contribution of reflection to total EMI SE also increases after the presence of GaInSn LM.