Laser-assisted one-step fabrication of interlayer-spacing-regulated three-dimensional MXene-based micro-supercapacitors.

• One-step fabrication of interlayer-spacing-regulated 3D micro-supercapacitors. • The precise fabrication of an interdigital micro-electrode structure. • Strong mechanical stability of the micro-electrode structure. • 3D MXene-rGO MSCs achieve a high areal capacitance. Three-dimensional micro-supercapacitors (3D MSCs) as microenergy-storage modules in miniaturized electronics exist complex construction strategies and limited assembly accuracy. Herein, we propose a one-step construction strategy of 3D MSCs with customizable layer spacing using two-dimensional (2D) film through laser direct writing technology. Laser shaping process induces a substantial enthalpy change, initiating a multi-step reaction that results in the reduction of graphene oxide while facilitating the rapid release of abundant gas generated by its functional groups. This results in an "explosion" of the MXene-graphene oxide (MXene-GO) film, thereby causing its transition from a 2D stacked structure to a 3D skeletal framework. The coexistence of MXene and reduced graphene oxide (rGO) sheets induces a heterogeneous film bonding effect, consolidating the loose and disordered MXene-rGO during the reduction process. When the current density is 0.9 mA cm−2, the area capacitance of 3D MXene-rGO MSCs reaches 66.69 mF cm−2, and its area energy density soars to an impressive 83.4 μW h cm−2, surpassing most of the reported 3D MSCs. Upon increasing the current density from 0.9 mA cm−2 to 1.7 mA cm−2, a remarkable capacitance retention rate of 74 % is achieved. This fabrication strategy promotes the development of next-generation 3D MSC with high performance. [ABSTRACT FROM AUTHOR]