Research On WO₃Lithium-ion Battery And Supercapacitor Electrode Materials

Due to fast charge and discharge, long life, maintenance-free, environment-friendlyfeatures, Lithium-ion batteries and supercapacitors have become a new types of powersupply options. In order to obtain a high performance lithium ion batteries andsupercapacitors, to develope an excellent electrode material is particularly importance.In this thesis, inexpensive tungsten trioxide was used as supercapacitors and lithium-ionbatteries electrode material and the lithium-ion battery and supercapacitor performancesof different morphologies of tungsten trioxide nanomaterial prepared by liquid phasemethod were studied systematically, and structural and electrochemical properties of theas-prepared nanomaterials also were investigated.(1) Two tungsten trioxide nanostructures, that is nanoflowers and nanoribbons,have been successfully synthesized by a facial hydrothermal method. Then theas-obtained produccts were tested for electrochemical galvanostatic charge–dischargecapacity at200mA g-1current density capacity of the cycle after180times were150mAh g-1and90mAh g-1, respectively. After the nanowires and nanoflowers were alsotested for their and a good rate capability were observed for two nanostructures.(2) Tungsten trioxide cloth-like structures composed of numerous nanowires weresuccessfully prepared by a facile hydrothermal method on carbon cloth. The uniquestructural features endow them with excellent electrochemical performance. The SCsdemonstrate high specific capacitance of521F g-1at1A/g and5.21F cm-2at10A cm-2and excellent cyclic performance with nearly100%capacity retention after2000cyclesat a current density of3A g-1. All-solid-state SCs based on the integrated electrodes arealso presented, exhibiting high flexibility without obvious performance declination atdifferent bending states. The lithium storage property of the sample was investigated.When cycling at a current density of0.28C, the WO3nanowire arrays on carbon clothshowed a reversible capacity as high as662mAh g-1after140cycles. Rate capability ofthe sample was studied by discharging/charging at various current densities. Areversible capacity of108mAh g-1was obtained even at a current density as high as5C. The high capacity, excellent cycling stability, and the good rate capability can beattributed to the unique morphology the good electrical conductivity of the carbon cloth.(3) WO3@SnO2heterostructures were synthesized by a facile, two-stephydrothermal method. WO3@SnO2heterostructures exhibit a high reversible capacity of1000mAh g-1after200cycles at a current density of0.28C, much higher than that ofthe WO3nanowire array，and the enhanced rate capability. The superior electrochemicalperformances of the heterostructures can be ascribed to the incorporation of SnO2,which decreases the overall battery internal resistance and improves the conductively ofthe electrodes.