Research On Graphene-based Flexible Micro-supercapacitors Based On Laser Scribing Technology

With the rapid development of small portable and flexible wearable electronic devices,there is an increasing demand for small energy storage devices.Microbatteries,as the first choice for self-powered microdevices,have shortcomings such as short service life and low power density.Therefore,vigorous development of micro-supercapacitors can overcome these shortcomings.In view of this,in this thesis,a fast,efficient,and non-contact laser scribing process was used to prepare shape-controllable graphene-based patterned electrodes on various flexible substrates and assemble them into flexible in-plane micro-supercapacitors（MSCs）.Finally,an in-depth study of their performance is carried out,which mainly includes the following contents:（1）The graphene oxide（GO）solution was prepared by the modified Hummers method,and then cured into a GO film on a flexible PET substrate.Through the laser scribing process,the laser scribing graphene oxide（LSG）was effectively reduced by the thermal polymerization effect of the laser.Flexible LSG patterned electrodes were fabricated and assembled into flexible in-plane MSCs.The morphology and structural characteristics of GO and LSG electrode materials were studied in detail by scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）and Raman spectroscopy.By studying the electrochemical properties of four different LSG patterned electrodes of interdigitated type,symmetrical type,square type and concentric circle type,the LSG patterned electrode with the best performance was obtained.The electrochemical energy storage characteristics of flexible interdigital LSG MSCs were studied in detail by cyclic voltammetry（CV）,galvanostatic charge-discharge（GCD）,electrochemical impedance spectroscopy（EIS）,mechanical flexibility and cycle stability.The results show that the interdigitated LSG MSCs exhibits very good energy storage properties,with a specific area capacitance of 3.74 m F·cm^-2,indicating that LSG MSCs have broad application prospects for wearable flexible electronic devices.Based on the curing and forming mechanism of polyimide（PI）film,MoS₂ nanoparticles were uniformly dispersed in liquid PI precursor（PAA）,and then cured at high temperature into MoS₂-doped PI film.The flexible patterned MoS₂/LIG composite electrodes were fabricated by a non-contact laser scribing process and assembled into flexible MSCs.The morphology and structure of the MoS₂/LIG composite electrode material were characterized by SEM,TEM,XPS and Raman spectroscopy.The electrochemical energy storage properties of flexible MoS₂/LIG MSCs were analyzed in detail from the aspects of CV,GCD,EIS,mechanical flexibility and cycle stability.The capacitance of the MoS₂/LIG MSC is 9.07 m F·cm^-2,ahead of many similar graphene-based supercapacitors fabricated by other processes.In this thesis,MoS₂ uniformly doped patterned LIG electrode material prepared by laser scribing process has excellent area specific capacitance,cycle stability and mechanical flexibility,and has great application prospects for integration into portable and wearable flexible electronic products.It has certain reference significance for design and micro-nano fabrication of flexible devices with different heterogeneous components uniformly embedded in LIG.