A novel structural design of shielding capsule to prepare high-performance and self-healing MXene-based sponge for ultra-efficient electromagnetic interference shielding

Structural design plays an important role in the fabrication of high-performance electromagnetic interference (EMI) shielding materials, as well as determining the shielding efficiency and the corresponding shielding mechanism. Herein, a unique structure based on the shielding capsules was built in a lightweight, flexible, and self-healing EMI shielding sponge through the simple dip-coating method. In brief, the perfect MXene membranes formed and covered the pores of the melamine sponge by precisely tuning the coating parameters, connecting the porous skeletons into plenty of shielding capsules. As a result of the significantly enhanced interaction chances between electromagnetic waves and MXene membranes, the prepared composite sponge possessed a high EMI shielding effectiveness (EMI SE) of 90.49 dB in the range of X-band (8.2–12.4 GHz) with a dominant contribution of SEA as high as 93% at an extremely low loading of Ti3C2Tx (0.82 vol%). In addition, the incorporation of polyurethane (PU) sandwich endowed the materials with a self-healing function. After a cut-off and healing cycle, the healed sponge still held a high EMI SE of 72.89 dB with a shielding efficiency of 99.999995% and supported 1475 times the weight of the sample itself. Therefore, the lightweight composite sponges with such shielding capsules have excellent EMI shielding and self-healing properties, showing the great application potential in portable and wearable devices.