| Supercapacitors have attracted extensive attention due to their many advantages.In order to meet the needs of current electronic devices in practical applications,the main research focus is to improve the energy density of the device while ensure high power density and stability.Electrode materials are significant for energy storage performance of the devices.Up to now,the research on supercapacitor cathode materials has been in-depth,negative electrode materials research is less,make the electrochemical properties do not match with the cathode materials.Therefore,design and synthesis of anode materials with high energy density is very imperious for energy storage devices.α-Fe2O3 is an ideal pseudocapacitor anode material,with the advantages of safety,environmental protection,good thermal stability and high theoretical specific capacity.But it shows poor conductivity and cycling stability.In order to address these issues,the current main solution is to buildα-Fe2O3 based nanocomposites by compoundingα-Fe2O3 with carbon or other pseudocapacitive materials through structural regulation.The electrochemical performance is enhanced by the synergistic effect between two materials.In this thesis,useα-Fe2O3 nanomaterials as research object,and the prepared electrode materials are studied from nanostructure of materials and composite with other materials two aspects,the main contents are as follows:（1）Uniform-sizedα-Fe2O3 nanosheets were grown on nickel foam by a simple solvothermal method,and thenα-Fe2O3@PPy-70 electrode material was prepared by a electrochemical deposition route.The polypyrrole-modifiedα-Fe2O3 nanosheet structure provides more conductive pathways,resulting in the improved electrical conductivity and cycling stability of the material.Using as-obtained composite as negative electrode,a flexible quasi-solid-state device was assembled.It possesses an energy density of 0.178 m Wh cm-3 and a power density of 7.09 m W cm-3.（2）Using carbon cloth as collector,α-Fe2O3@Mn O2 nanorod arrays were prepared by a hydrothermal method and subsequent electrochemical deposition.The products delivers a maximum specific capacity of 992.6 m F cm-2(2 m A cm-2).After 10000 cycles at 4 m A cm-2,the capacity retention is 92.3%.The assembled supercapacitor presents an energy density of0.245 m Wh cm-3 at power density of 10.01 m W cm-2.（3）α-Fe2O3@Fe S2 nanocrystals were prepared by a facile one-step hydrothermal method.This nanostructure can effectively utilize the large specific surface area,reasonably improve the ion exchange efficiency.At 2 m A cm-2,the specific capacitance reaches 1155.74 m F cm-2.And the energy density of the device can reach 1.12 m Wh cm-3and the power density is 27.99 m W cm-2(2 m A cm-2). |
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