Microstructure Design Of Flexible Conductive Film For Energy Storage And Electromagnetic Interference Shielding Application

With the concepts of wearable devices,implantable bioelectronics,electronic skin,and Intelligent electronic fabrics being put forward,flexible electronic devices have become the focus of scientific and commercial circles.Because they are likely to trigger another revolution in human lifestyles.Therefore,the research and development of flexible conductive film（FCFs）with high performance has become the mission of every researcher in the era of flexible electronics.FCFs have high research value and application potential in the fields of energy storage and electromagnetic interference（EMI）shielding because of good electrical conductivity,flexibility,adaptability and structural stability.In order to further improve the performance of FCFs,most of researches still focus on the way of material innovation or material composition.However,this way not only increase the cost and difficulty of preparation,but also is not extend to the preparation of other materials.Herein,A low cost,simple process and extended FCFs microstructure design is of great significance in achieving performance improvement and even breakthrough.In view of the existing problems of FCFs,in this thesis,the flexible free-standing three-dimensional flower-like polypyrrole/5,10,15,20-tetrakis（4-carboxylphenyl）porphyrin copper（II）（TF-PPy/Cu-TCPP）nanocomposite film with hierarchical PPy micro flower arrays and Ti₃C₂ film with with ordered stacked layered structure are prepared and further improves the energy storage performance and EMI shielding performance while ensuring flexibility.The specific content is as follows:1.Research on preparation and Energy Storage of 3D TF-PPy/Cu-TCPP ElectrodeTwo-dimensional（2D）PPy film cannot further improve the energy storage performance due to the dense structure and the hindrance of charge transport.3D TF-PPy/Cu-TCPP nanocomposite electrode has been fabricated via the combination of electrophoretic deposition and electrochemical polymerization（ECP）and assembled into all-solid-state symmetric supercapacitors（SCs）.The growth mechanism is involved in the following aspects.I)The wrinkled Cu-TCPP nanosheets provide abundant porous channels to facilitate the immersion of pyrrole molecules and uniform cross-linking of PPy.II)The rough surface of the PPy/Cu-TCPP composite film provides rough sites for the growth of hierarchical TF-PPy arrays under the assistance of H₂ bubbles.The collaborative advantages of 3D conductive networks and the hierarchical TF-PPy arrayed on the rough surface of electrode facilitate the fast ion/electron transport for the enhanced electrochemical performances.The corresponding TF-PPy/Cu-TCPP electrode shows an areal capacitance of 593 m F cm^-2 at 0.5 m A cm^-2,which is superior to the PPy/Cu-TCPP electrode(351 m F cm^-2)and the pristine PPy(287 m F cm^-2).The symmetric supercapacitor exhibits the energy density of 5.94μW h cm^-2 at a highest power density of 25μW cm^-2.This work provides guidance for the optimization of energy storage performance by designing and constructing FCFs electrodes with 3D microstructure.2.Research on design and EMI shielding of ordered stacked layered structure of Ti₃C₂ filmTi₃C₂ films further improve EMI shielding effectiveness（SE）by increasing thickness or load.A multiscale layered structure optimization strategy is proposed to enhance EMI shielding performance through orderly superimposing individual free-standing Ti₃C₂ film.The superimposed Ti₃C₂（S-Ti₃C₂）films on the macroscopic scale exhibit higher EMI SE than the bulk F-Ti₃C₂ film with the same weight in the X-band frequency range（8.2～12.4 GHz）.Compared to a bulk F-Ti₃C₂ film（64.6 d B）with the same weight of 150 mg or a bulk F-Ti₃C₂ film（60.3 d B）with the same thickness of 24μm,the S-Ti₃C₂-6 show much higher EMI shielding performance（84.7 d B）.The shielding mechanism is ascribed to the synergistic effect of multiple internal reflections between Ti₃C₂ nanosheets and multiple-wave interference between adjacent F-Ti₃C₂ films.Furthermore,the increment in the gap distance（d）between the adjacent F-Ti₃C₂ films can also increase the 46.6%EMI SE from 51.1 d B（d=0 mm）to 74.9 d B（d=1.5 mm）.Therefore,the regulation of EMI SE can be realized by designing the d of S-Ti₃C₂.Furthermore,the multi-layered design strategy can be extended to other EMI materials including polypyrrole and graphite,etc.This work provides a guide for the optimization of EMI shielding performance by designing and constructing FCFs with ordered stacked layered structure.