High‐efficiency electrothermal and electromagnetic interference shielding performance of expanded graphite/silicone film

Expanded graphite (EG) is a desired filler for electrothermal and electromagnetic interference (EMI) shielding because of its easy access, low‐cost, lightweight, high conductivity, and heat sensitivity. Herein, fluffy EG was prepared from natural flake graphite (NFG) by a simple expansive technology and subsequently heat treatment at 800°C for 2.0 h in 5% Ar/H2 atmosphere. EG/silicone films with a filling ratio of 15 wt% were obtained via hot‐pressing, which exhibited sensitive electrothermal and excellent EMI shielding performances. When the applied voltages were 5.0, 10.0, and 15.0 V, the steady‐state temperatures were 54.0, 136.5, and 237.8°C in the 30s, respectively. Meanwhile, their average EMI shielding efficiency was greater than 20 dB in 2–18 GHz at 0.84 mm, which was 6.3 times as much as NFG/silicone film. Therefore, this study offers a simple and effective strategy for preparing excellent electrothermal‐EMI shielding materials.Highlights Fluffy EG is prepared by a simple expansive method and treatment at 800°C. EG/silicone films exhibit good electrothermal and EMI shielding performances. Steady temperatures of 55.0/136.5/237.8°C are gotten at 5/10/15 V in 30 s. The EMI shielding efficiency is greater than 20 dB at 0.84 mm. Good properties are due to the EG with high conductivity and fluffy structure.