Scalable 3D Self‐Assembly of MXene Films for Flexible Sandwich and Microsized Supercapacitors

Abstract The self‐assembly of large‐area MXene films is the main step to realize their applications in various energy storage devices. However, the scalable self‐assembly of flexible thin MXene films with high conductivity as well as excellent mechanical and electrochemical properties is still a challenge. Herein, a synchronous reduction and self‐assembly strategy to fabricate flexible MXene films is developed, where MXene films are synchronously reduced and self‐assembled on the Zn foil surface. Furthermore, the self‐assembly of MXene films can be scaled up by controlling the area of Zn substrates. By adjusting the patterns of Zn substrates, the interdigital MXene patterns can also be obtained via a selectively reducing/assembling process. The resultant MXene films demonstrate high electrical conductivity, large specific surface area, and excellent mechanical properties. Thus they can serve as the electrodes of flexible supercapacitor devices directly. As a proof of concept, flexible sandwich and microsized supercapacitors are designed based on the above MXene film electrodes. Both sandwich and microsized supercapacitors display stable electrochemical performance under various bending states. This study provides a route to achieve large‐area MXene‐based films or microsized structures for applications in the field of energy storage.