The re-stacking of Ti₃C₂T_x-MXene layers has been prevented by using two different approaches: a facile hard templating method and a pore-forming approach. The expanded MXene obtained by using MgO nanoparticles as hard templates displayed an open morphology based on crumpled layers. The corresponding electrode material delivered 180 F g⁻¹ of capacitance at 1 A g⁻¹ and maintained 99% of its initial capacitance at 5 A g⁻¹ over five thousand charge-discharge cycles. On the other hand, the MXene foam prepared after heating a MXene-urea composite at 550°C, showed numerous macropores on the surface layer and a complex open 3D inner-architecture. Thanks to this foamy porous structure, the binder-free electrode based on the resulting MXene foam displayed a great capacitance of 203 F g⁻¹ at 5 A g⁻¹ current density, 99% of which was retained after five thousand cycles. In comparison, the pristine MXene –based electrode delivered 82 F g⁻¹, only, in the same operating conditions. An asymmetric device built on a negative MXene foam electrode and a positive MnO₂ electrode exhibited an attractive energy density of 16.5 Wh kg⁻¹ (or 10 Wh L⁻¹) and 160 W kg⁻¹ (or 8.5 kW L⁻¹) power density. Altogether, the enhanced performances of these nano-engineered 2D materials are a clear demonstration of the efficiency of the chosen synthetic approaches to work out the re-stacking issue of MXene layers.

通过使用两种不同的方法可以防止Ti ₃ C ₂ T _x -MXene层的重新堆叠：简便的硬模板方法和成孔方法。通过使用MgO纳米颗粒作为硬模板获得的膨胀MXene显示出基于皱褶层的开放形态。相应的电极材料在1 A g ^-1时提供180 F g ^-1的电容，并在5 A g ^-1时保持其初始电容的99％超过五千次的充放电循环。另一方面，在将MXene-脲复合物在550℃下加热之后制备的MXene泡沫在表面层上显示出许多大孔和复杂的开放式3D内部结构。由于这种泡沫多孔结构，基于所得的MXene泡沫的无粘合剂电极在5 A g ^-1电流密度下显示出203 F g ^-1的大电容，经过五千次循环后仍保留了99％。相比之下，原始的MXene基电极在相同的操作条件下仅输出82 F g ^-1。建立在负极MXene泡沫电极和正极MnO ₂电极上的不对称器件的吸引力能量密度为16.5 Wh kg ^-1（或10 Wh L ^-1）和160 W kg ^-1（或8.5 kW L ^-1）的功率密度。总而言之，这些纳米工程二维材料的增强性能清楚地证明了所选择的合成方法可有效解决MXene层的重新堆叠问题。