Highly conductive graphene film with high-temperature stability for electromagnetic interference shielding

Lightweight, flexible and highly conductive electromagnetic interference (EMI) shielding materials are urgently needed to protect the electronic and telecommunication devices from interference failure. Carbon-based films have attracted much interest to provide EMI shielding with minimal thickness in recent years, particularly exemplified by macroscopic graphene film. However, the inferior electrical conductivity to metal or the un-stability of doped graphene film cannot meet the ever-growing demands for harsh environment applications. Here, we prepare highly conductive copper chloride intercalated graphene film (GF-CuCl2) with high-temperature stability up to 400 °C. The intercalation of CuCl2 significantly improves the hole density, and the achieved electrical conductivity (1.09 × 107 S m−1) is nearly 10 times that of pure graphene film. The ultra-low temperature coefficient of resistance (4.31 × 10−4 K−1) makes GF-CuCl2 electrically stable over a broad temperature range. A 35-μm-thick GF-CuCl2 exhibits an average EMI shielding effectiveness of ∼110 dB from 2 to 18 GHz and ∼126 dB from 8.2 to 12.4 GHz, which is the highest among materials of comparable thickness. Moreover, the EMI shielding capability of GF-CuCl2 shows long-term durability under extreme conditions. All these characteristics demonstrate the GF-CuCl2 is suitable for the practical EMI shielding applications.