Research On The Preparation And Electromagnetic Shielding Performance Of Laser-induced Graphene/nickel Composite Materials

The rapid development of modern wireless communication and electronic telecommunication equipment is accompanied by harmful electromagnetic interference(EMI),which seriously threatens the health of living organisms and the normal operation of other sophisticated electronic equipment.Since the discovery of EMI shielding materials,metal-based EMI shielding materials have been the main choice.Except for magnetic metals(such as Fe,Ni and Co),other metals mainly reflect EM waves through the vector interaction of a large number of charge carriers on the surface and incident EM waves,so as to achieve the shielding effect.However,this will cause secondary EM waves pollution.EMI shielding materials that minimize the reflection of EM waves by increasing the absorption performance are very suitable for radar shielding and stealth technology.Therefore,research on absorption-dominated high-performance EMI shielding materials with both flexibility and portability has great theoretical significance and practical application value.In this paper,a composite EMI shielding material with nickel nanoparticles loaded on a three-dimensional porous LIG was prepared by combining laser-induced graphene(LIG)technology and pulsed electrodeposition technology.By determining the optimal parameters,a high efficiency absorption-dominant EMI shielding composite material with flexibility and high stability is obtained.The influence of laser parameters and electrodeposition time on EMI shielding has been systematically studied.Meanwhile,the influence of porous structure on electromagnetic shielding and the shielding mechanism of absorption-dominant are discussed in depth.Experimental results show that three-dimensional porous graphene is generated by laser pyrolysis on a polyimide film.Single laser-induced graphene(S-LIG)possess an EMI shielding effectiveness of 25 d B and an average absorption rate of 64%.Double laser-induced graphene(D-LIG)possess better performance due to its improved graphene quality and greater thickness,with an EMI shielding effectiveness of 31 d B and an average absorption rate of 69%.Compared with single laser-induced graphene(S-LIG),double laser-induced graphene(D-LIG)has improved graphene quality and greater thickness,which has a higher EMI shielding effectiveness.D-LIG/Ni composite materials with absorption as the main shielding mechanism were prepared by uniformly depositing nickel nanoparticles on the three-dimensional conductive network of D-LIG.The optimized single-layer(0.195 mm)D-LIG/Ni composite material has an EMI shielding effectiveness of 55 d B in the X band(8.2-12.4 GHz),an average absorption rate of 82%,and high stability(The EMI SE retention rate after 500 bending is 89%).The doublelayer(0.327 mm)D-LIG/Ni composite material possess an EMI shielding effect of up to79 d B with an absorption rate of 86%.The study of the electromagnetic shielding mechanism shows that the multiple reflections of EM waves inside the porous composite extend its transmission path and increase the possibility of dissipation.Ultimately,the best match between the dielectric loss and the magnetic loss results in a high absorption capacity.The comprehensive electromagnetic shielding effectiveness(thickness,EMI SE,absorption rate)of the prepared composite material is far better than most carbon-based EMI shielding materials.It can be expected that the as-prepared material with flexibility,stability,high performance EMI shielding and high absorption rate has a wide range of application prospect in the fields of military,aerospace,and micro flexible devices.