High-strength nacre-like composite films based on pre-polymerised polydopamine and polyethyleneimine cross-linked...

Demands for high-strength flexible electrodes have significantly increased across various fields, especially in wearable electronics. Inspired by the strong integrated layered structure of the natural nacre via multi-bonding interactions, we report the fabrication of the strong integrated nacre-like composite films based on pre-polymerised polydopamine and polyethyleneimine cross-linked MXene layers (p-DEM), achieving the synergic effect of hydrogen bonding, covalent bonding and electrostatic interactions. As a result, a high-level tensile strength of ∼302 MPa, 10.8 times higher than that of the plain MXene film, is obtained for the prepared p-DE_0.5M composite film. Meanwhile, the composite film also delivers superior energy storage (∼1218F cm^-3 at 5 mV s^-1) and rate performances (capacitance retention of 81.3% at 1000 mV s^-1). To demonstrate the practical application of the composite films, a symmetrical supercapacitor based on p-DE_0.5M electrodes is assembled, which shows stable energy storage performances under different deformation states such as bending angles at 0, 60, 90 and 180°, or withstand repeated bending times (1000 cycles). This type of multi-bonding interactions induced strong integrated MXene assembly may promote the wide applications of MXene-based films in flexible electronics, artificial intelligence, and tissue engineering, to name a few.