Study On The Properties And Preparation Of Printed FeOOH/Graphene Microsupercapacitors

Microsupercapacitors?MSCs?,have attracted considerable attention in recent years because of their high power density,fast charge-discharge rates and excellent cycle life.Fe OOH has been a research focus with variable oxidation state,high theoretical specific capacitance?up to 2606 F/g?and naturally abundant.The poor conductivity( 10^-14 S/cm)of Fe OOH electrode materials,however,has limited the development of Fe OOH-based MSCs.In this work,the electrochemical properties of Fe OOH-based MSCs,are improved by the combination of amorphous Fe OOH and highly conductive graphene.Fe OOH and Fe OOH/graphene composites with amorphous structure were successfully prepared by simple hydrothermal method,and we systematically investigated their electrochemical properties using cycle voltammetry?CV?,galvanostatic charge-discharge?GCD?and electrochemical impedance spectroscopy.The planar interdigital micro-supercapacitor was printed by combining with the gravure printing technology,at the same time,and optimizing the printing process.The main research contents and results as follows:Firstly,the Fe OOH nanoparticles were successfully prepared by simple hydrothermal method.The characterization and analysis of Fe OOH samples with scanning electron microscopy?SEM?and transmission electron microscopy?TEM?,which showed that the Fe OOH samples were uniformly distributed nanoparticles and had an amorphous structure.Amorphous Fe OOH can improve the transport of electrolyte ions than high-crystalline counterpart due to their high structural disorder,which exhibits excellent electrochemical properties.In addition,gravure printing technique combined with the Fe OOH ink was successfully prepared a printed interdigital Fe OOH-based MSCs.By electrochemical test,the Fe OOH electrode prepared has a specific capacitance up to 578 F/g at a current density of 1 A/g.And a printed Fe OOH device achieves an area specific capacitance of 9.3 m F/cm² and area energy density of 0.83 ?Wh/cm² at a scan rate of 5 m V/s.Secondly,the in-situ hybridization of amorphous Fe OOH nanoparticles with highly conductive graphene was carried out by hydrothermal method.The Fe OOH/graphene composite was successfully prepared,and Fe OOH/graphene composite ink was further prepared for the electrode material of printed MSCs.It was found that the amorphous Fe OOH nanoparticles were grown in-situ on the graphene nanosheets through the SEM analysis of the composite electrode,which is effectively to prevent the agglomeration of graphene sheets,therefore,increasing the sufficient contact area of the electrolyte solution with the graphene and Fe OOH nanoparticles.The sufficient contact area of the particles,in turn,provides more ion transport channels that synergistically enhance the electrochemical performance of the composite.The plane interdigitated Fe OOH/graphene MSCs printed by the gravure printing obtained an area specific capacitance of 7.4 m F/cm² and energy density of0.66 u Wh/cm² at a scanning rate of 5 m V/s.When the device was subjected to 1500 bendable tests,it still retained 77% of the initial specific capacitance,and exhibited excellent cycle stability.Which shows that Fe OOH/graphene composite in this study is expected to serve as electrode material for micro-supercapacitors..In this work,we synthesized Fe OOH/graphene composites on graphene nanosheets using a simple hydrothermal method.A flexible planar interdigitated micro-supercapacitor was successfully fabricated by gravure printing technology.It provides a reference for the research of printed miniature supercapacitors.