High-efficiency electromagnetic interference (EMI) shielding composite films (EMI shielding effectiveness (SE) value > 100 dB) with a small thickness are imminently desired for eliminating the serious electromagnetic wave pollution. Herein, asymmetric sandwiched silver-coated four-needle zinc oxide whisker/nanofibrillated cellulose/TiCT (F-ZnO&Ag/NFC/TiCT) composite films consisting of the loose F-ZnO&Ag sedimentary layer and compact upper TiCT layer were successful fabricated by a facile one-pot vacuum filtration method in combination with gravity-induced delamination. Arising from the favorable electrical conductivity and unique asymmetric sandwich structure, electromagnetic waves can be trapped and dissipated in the F-ZnO&Ag skeletons and strongly multiply reflected between top TiCT layer and bottom F-ZnO&Ag layers. Thereby, F-ZnO&Ag/NFC/TiCT-30.4 exhibits the ultrahigh averaged EMI SE of 103.9 dB (the maximal value of 123.8 dB) at a low thickness of merely 209 μm, which is far superior to that of almost all the reported NFC composites at the similar thickness to date. In the real EMI shielding application test, composite films are confirmed to block signal transmission and switch off the toy car system. Such simple and high-efficiency asymmetric sandwich structure design makes a great progress towards preparing and adjusting thin EMI shielding composite films for the promising application prospects in advanced electronics and communication technology.

中文翻译：

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一锅真空过滤制备不对称夹心纳米原纤纤维素复合材料用于超高电磁干扰屏蔽

为了消除严重的电磁波污染，迫切需要小厚度的高效电磁干扰（EMI）屏蔽复合薄膜（EMI屏蔽效能（SE）值> 100 dB）。在此，通过一种简便的方法成功制备了由松散的F-ZnO&Ag沉积层和致密的上TiCT层组成的不对称夹心银包四针氧化锌晶须/纳米原纤化纤维素/TiCT（F-ZnO&Ag/NFC/TiCT）复合薄膜。 -罐式真空过滤法与重力诱导分层相结合。由于良好的导电性和独特的不对称夹层结构，电磁波可以在 F-ZnO&Ag 骨架中被捕获和消散，并在顶部 TiCT 层和底部 F-ZnO&Ag 层之间强烈多重反射。因此，F-ZnO&Ag/NFC/TiCT-30.4在仅209 μm的低厚度下表现出103.9 dB的超高平均EMI SE（最大值123.8 dB），远远优于几乎所有报道的NFC复合材料迄今为止相似的厚度。在真实的EMI屏蔽应用测试中，复合薄膜被证实可以阻挡信号传输并关闭玩具车系统。这种简单高效的非对称夹层结构设计在制备和调节薄型EMI屏蔽复合薄膜方面取得了重大进展，在先进电子和通信技术中具有广阔的应用前景。