Preparation And Energy Storage Properties Of Graphene Nanocomposites

At present,traditional energy use methods and storage technologies can no longer meet people's needs,and there is an urgent need to develop more efficient energy conversion and storage-related new technologies.Common sustainable green energy sources have seasonal and intermittent characteristics.Therefore,there is a need for an alternative energy storage device with a higher capacity.Supercapacitors are one of the most promising candidates for energy storage devices due to their many essential advantages.It has common electric double layer capacitor materials and pseudocapacitor materials,which have their own advantages and disadvantages.Graphene is one of the ideal materials for double-layer capacitors because it has the best electrical conductivity,thermal conductivity,unit strength and specific surface area,etc.However,when the graphene is used alone as a supercapacitor electrode material,it has disadvantages such as low capacitance and easy agglomeration as well.In this paper,graphene oxide was prepared by the Hummers separation graphite method,and then composite electrode materials such as Fe Ni₃/r GO,Ti O_x/r GO and Ni Co₂O₄/r GO/Fe₃O₄ were sythesised by one-step hydrothermal reduction,solid-phase reduction and co-precipitation.Its microstructure and morphology and other physical and chemical properties were characterized by TEM,FESEM,EDS,XRD,XPS,FTIR,Raman,TGA and other methods,and their related electrochemical energy storage performance was analyzed and studied.The results showed that the FeNi₃/rGO composite was prepared by a one-step hydrothermal reduction method;the specific capacitance was 169.42F/g at 10m V/s scanning rate,which is higher than that of Fe Ni₃ and r GO materials alone.In addition,the composite consisted of Ti O_x nanorods and r GO was prepared by a two-step method of hydrothermal and solid-phase reduction methods.The specific capacitance was 149.5F/g at 40m V/s scanning rate.Remarkably,the specific capacitance of the Ti O_xNRs/r GO composite was still retained the original 89.57%after 2,000 cycles at a rate of 1A/g.Moreover,a Ni Co₂O₄/r GO multilayer flower-like structure composite was prepared by hydrothermal and co-precipitation methods.The average diameter of the micro-flowers was about 10?m,and the petals were evenly decorated with Fe₃O₄ nanoparticles with an average diameter of 10nm.Especially,the electrochemical response window of the final Ni Co₂O₄/r GO/Fe₃O₄composite is wider(-1.3?0.4V).At the scanning speed of 10m V/s,and the calculated specific capacitance was 309.4F/g.In this paper,Ni Co₂O₄/r GO/Fe₃O₄ micron flower-like ternary composites interspersed with Fe₃O₄ nanoparticles have been prepared innovatively,and the electrochemical test shows that it has excellent energy storage performance.