The Preparation And Supercapacitor Performance Study Of Iron Doped Tungsten Oxide Nanowire

Supercapacitors（SCs）are regarded as an important support to promote the development of energy storage technology due to their advantages such as fast charging and discharging capability,high power density,long cycle stability and good safety.Tungsten trioxide（WO₃）has advantages of high theoretical capacity and fast redox reaction rate,and its application as electrode material in the field of supercapacitors has good prospects.However,the sluggish intrinsic carrier transport kinetics and poor structural stability of WO₃ are the key issues limiting its further development.To address the above challenges,this paper utilizes heteroatom doping and controlled cladding to regulate the carrier transport kinetics and structural stability of WO₃,and explores the preparation methods and design principles of high performance WO₃-based electrode materials as follows:Fe-doped WO₃ array electrodes（Fe-WO₃@CC）with different doping concentrations were synthesized on carbon cloth substrate by simple physical immersion,hydrothermal method and subsequent annealing process,and the effects of different doping ratios on the morphological structure and electrochemical properties of WO₃ were investigated.The results show that when the molar ratio of Fe to W is greater than 1:20,the morphology changes from the original nanorod to nanowire,which greatly shortens the ion diffusion path.Doping can effectively improve the electrochemical performance of WO₃ by changing the electron/ion structure and bringing an abundance of additional active sites for energy storage.The electrochemical performance is optimal when the molar ratio of Fe to W is 1:10（10%Fe-WO₃@CC）,and 10%Fe-WO₃@CC exhibits 3480 m F cm^-2 area-specific capacitance at a current density of 5 m A cm^-2,which is nearly 5 times higher than that of pure WO₃,and can remain 92.7%capacitance retention after 10,000 cycles.Although doping has improved the specific capacitance of the material,the improvement of the multiplicative performance is not obvious,so further modification of the electrode material is needed.10%Fe-WO₃ electrode was used as a precursor and a controlled coating of polyaniline（10%Fe-WO₃@PANI）was designed on it by a process method of electrodeposition.The coated polyaniline（PANI）enhances the structural durability of WO₃ in acidic electrolyte during charging/discharging.The calculation shows that the capacitance retention rate of 10%Fe-WO₃@PANI electrode is 54.11%,which is about21%higher than that of 10%Fe-WO₃ electrode.The multiplier performance is greatly improved,and the electrode can work stably for 10000 cycles without obvious capacitance decay.In addition,the PPy//10%Fe-WO₃@PANI solid-state asymmetric supercapacitor was assembled with 10%Fe-WO₃@PANI as the negative electrode and polypyrrole（PPy）as the positive electrode,and the maximum energy density could reach 70.25μWh cm^-2 at a power density of 2.42 m W cm^-2,showing excellent performance.