Design,Preparation And Electrochemical Performance Of Iron Group Metal Composite Materials

Two composite electrode materials were prepared in this paper,composite materials of multi-wall carbon nanotubes?MWCNTs?and iron and manganese metal oxides and composite materials of nickel,cobalt metal sulfides and iron metal oxide,the electrochemical properties of two electrode materials in supercapacitors were studied separately.The main research contents are as follows:1.Fe₃O₄/CNTs@MnO₂ supercapacitor negative electrode material with a three-dimensional network structure was synthesized by a simple hydrothermal method.Carbon nanotubes,as the substrate for growing Fe₃O₄ nanoparticles,are surrounded by MnO₂ film.The tightly connected phases and the three-dimensional structure can provide multiple channels for the transmission of ions and electrons.In addition,the three-dimensional nanostructure has a large specific surface area,which increases the reactive sites,thereby greatly improving the electrochemical performance.Therefore,when it is used as an electrode of supercapacitor,Fe₃O₄/CNTs@MnO₂ has a high specific capacitance of 643.8 F g^-11 at 1 A g^-1.And it has excellent cycle stability(the specific capacitance is 283.3 F g^-1 at 3 A g^-1 after 5000 cycles).The assembled symmetric supercapacitor?SSC?device?Fe₃O₄/CNTs@MnO₂//Fe₃O₄/CNTs@MnO₂?has a high energy density of 52.98 Wh kg^-1 at a power density of 847.9 W kg^-1 and a good cycle stability(the specific capacitance retention is 63%at 1 A g^-1 after 10000cycles).It is worth mentioning that the capacitance retention rate has not been changed from the 2000th cycle to the 10000th cycle.2.A simple stirring method was used in the experiment to grow a NiS/Co₃S₄nanosheet structure on the surface of the precursor of Fe₂O₃ nanoparticles to prepare a Fe₂O₃@NiS/Co₃S₄?Fe₂O₃@Ni1Co1-S?electrode.The nano-electrode material itself has more electrochemical active sites,so the Fe₂O₃@Ni1Co1-S electrode exhibits higher electrochemical performance.In addition,the electrode exhibits a high specific capacitance value of 1213.7 F g^-1 at a current density of 1 A g^-1,and has excellent cycling performance(after 5000 cycles,the retention rate is 81%at 5 A g^-1).In order to further study the practical applicability of this electrode material,when assembled into a asymmetric supercapacitor Fe₂O₃@Ni1Co1-S?positive?//AC?negative?,the device has a power density of 1125 W kg^-1 at a current density of 1 A g^-1 and the energy density is37.4 Wh kg^-1.Therefore,Fe₂O₃@Ni1Co1-S has great potential as an electrode material for supercapacitors.These materials are prepared by simple and environmentally friendly methods and the prepared composite materials exhibit excellent electrochemical properties.Therefore,our work provides a new strategy for the preparation of supercapacitor materials based on iron group metals.