Ti₃C₂T${}_x$ MXene films exhibited good electromagnetic interference (EMI) shielding performance. However, the poor mechanical property and durability of Ti₃C₂T${}_x$ MXene films limited their commercial application. Herein, the ultrathin flexible conductive MXene/cellulose nanofiber (CNF)/MXene composite films with “sandwich” structure were successfully prepared by a simple vacuum-assisted filtration process. The addition of CNF can shield more electromagnetic microwaves (EMWs) via multiple reflections in the inner space and enhance the mechanical property of composite films by effectively welding the loosely MXene together. The composite film exhibited excellent EMI shielding effectiveness (up to 54.68 dB) at an ultrathin thickness (about 76 $\mu$m) as well as high electrical conductivity (up to 1610.51 S/m), which was mainly attributed to the hierarchical lamellar “sandwich” structure, where CNF was bonded to Ti₃C₂T${}_x$ MXene. The prepared flexible conductive composite films with brilliant EMI shielding effectiveness and good mechanical property possessed promising potential in various fields such as electromagnetic wave protection, weaponry and wearable electronics.

钛_3C2T _ _{_} _${}_X$MXene薄膜表现出良好的电磁干扰（EMI）屏蔽性能。但Ti ₃ C ₂ T的力学性能和耐久性较差${}_X$MXene 薄膜限制了其商业应用。在此，通过简单的真空辅助过滤工艺成功制备了具有“三明治”结构的超薄柔性导电MXene/纤维素纳米纤维（CNF）/MXene复合薄膜。CNF的添加可以通过内部空间的多次反射屏蔽更多的电磁微波（EMW），并通过有效地将松散的MXene焊接在一起来增强复合薄膜的机械性能。该复合薄膜在超薄厚度（约76$\mu$m）以及高电导率（高达1610.51 S/m），这主要归功于分层层状“三明治”结构，其中CNF与Ti 3 C ₂ T_键合${}_X$MXene。所制备的柔性导电复合薄膜具有优异的EMI屏蔽性能和良好的机械性能，在电磁波防护、武器装备和可穿戴电子等领域具有广阔的应用前景。