Fabrication Of AgNWs-Ti₃C₂T_x Composite Films With Excellent Electromagnetic Shielding Performance

With the development of the electromagnetic shielding field,the disadvantages of traditional metals and other materials are gradually increasing,so there is an urgent need for materials with excellent electromagnetic shielding performance,good mechanical properties and stability to satisfy the electronic equipment and human health.After the discussion in this article,composite materials will become the future development trend of electromagnetic shielding materials,and the high performance of lightweight composite materials and the convenience it brings have become the current research direction.In this paper,a light-weight composite material is used as a blueprint.A highly conductive and highly porous AgNWs/Ti3C2Tx composite film is designed.The electromagnetic shielding performance,mechanical performance and stability of the composite film are thoroughly studied,and its main shielding mechanism is explored.This paper mainly includes the following aspects:(1)First,for the problem of material selection,we studied the effects of AgNWs with different diameters and Ti3C2Tx with different thicknesses on the films final prepared,especially the effect of electrical conductivity.The study show that the films prepared with thicker AgNWs have higher electrical conductivity,and the films prepared with AgNWs with a diameter of～150 nm(thick nanowires)have a conductivity of about 12345 S/cm.This is mainly because the larger cross-sectional area of the larger diameter AgNWs lead to the smaller the resistance to a single AgNW.The film prepared by Ti3C2Tx after peeling(few layers Ti3C2Tx)has a higher electrical conductivity as well,which is about 1793 S/cm.This is mainly due to the reduced collision probability and electron mobility of the Ti3C2Tx film with few layers.So the thick nanowires and few layers Ti3C2Tx were selected as raw materials for subsequent experiments.(2)Second,the agglomeration problem generated when AgNWs is combined with Ti3C2Tx and the main shielding mechanism of the AgNWs/Ti3C2Tx-3/1 composite film were studied.The study show that the addition of PVP to the AgNWs/Ti3C2Tx dispersion can effectively improve the agglomeration problem when they are mixed,and then we made the AgNWs/Ti3C2Tx composite film with a skeleton network-decoration structure by suction filtration.Due to the synergistic enhancement of the skeleton network(AgNWs)and the decoration(Ti3C2Tx),the composite film has ultra-high electrical conductivity(15038 S/cm),strong internal multiple internal reflections,and low density(1.0-1.2 g/cm3),as well as good oxidation resistance,resistance to ultrasonic agitation and mechanical stability,these favorable properties lead SSE/t(X band)up to 301723 dB cm2 g-1,EMI SE(X band)is 46.1 dB at a thickness of 1.2 μm(or 77.9 dB at a thickness of 11 μm).(3)Finally,we studied how to further enhance the electromagnetic shielding performance of AgNWs/Ti3C2Tx composite film by improving the conductivity.One is to use NaOH as a pH regulator in stead of PVP to obtain a stable AgNWs/Ti3C2T,hybrid ink.The study found that when the pH value of the AgNWs/Ti3C2Tx hybrid ink can be stable in the range of 7.0～8.7,and the conductivity of the film prepared by negative pressure suction filtration can reach 36001 S/cm,which is a significant improvement compared to the previous 15038 S/cm conductivity of the AgNWs/Ti3C2Tx-3/1 composite film.The second is to use the positive pressure filtration method instead of the original negative pressure suction filtration method to prepare the AgNWs/Ti3C2Tx composite film.The study show the conductivity of AgNWs/Ti3C2Tx-10%composite film prepared by positive pressure filtration at 0.5 MPa for 3 min can reach 50281 S/cm.The EMI SE and SE/t of AgNWs/Ti3C2Tx-10%composite film are 62.8 dB,570909 dB cm-1 and 98.1 dB,89181 dB cm-1 at the thickness of 1.1 μm and 11 μm respectively;meanwhile,the mechanical performanceof this composite film has also been effectively improved.