Study On Preparation Of Heterostructure Cobalt-Based Nanowire Electrode Materials And Supercapacitor Performance

As a high power density,long life,and repeatable charging and discharging energy storage device,ultracapacitors have a wide application prospect.However,in practical applications,the energy density of supercapacitors is still relatively low and the operating voltage is relatively small,which limits their practical applications in certain scenarios.In this paper,we devote ourselves to improving the electrochemical performance of supercapacitors by optimizing the electrode materials through iron doping of cobalt trioxide,and also constructing cobalt-based nanowire heterostructured electrode materials in the form of high-temperature nitriding to further improve their electrochemical performance.Fe-doped Co₃O₄（Fe-Co₃O₄）nanowire arrays were prepared by facile hydrothermal method,and corresponding microstructure was characterized.The electrochemical properties and energy storage mechanism were analyzed.It was found that Fe doping optimized the original nanowire morphology and transformed it into a unique urchin-like nanowire structure;this unique urchin-like structure provided more active sites and larger specific surface area compared to the pristine nanowire morphology,which increased the contact area between the electrode and the electrolyte,leading to excellent energy storage kinetics.Furthermore,the urchin-like nanowire structure had better structural stability than that of the pristine nanowire structure.The urchin-like structure shows highly dispersed structure,efficiently prevented interaction between nanowires and reduced nanowire aggregation,exhibiting improved electrochemical stability and lifespans.As a result,the optimized Fe-Co₃O₄ electrode achieved a high specific capacitance of 620.5F/g at a current density of 4 A/g.To further improve the electrochemical performance of the Fe-Co₃O₄ electrode,Fe-Co₃O₄/Fe-Co₂N heterostructure nanowire arrays was designed through high-temperature nitridation,and the structure and electrochemical performances were thoroughly investigated.The difference in bandgap and Fermi energy between Co₃O₄ and Co₂N creates a built-in electric field around the heterointerfaces,promoting ion diffusion kinetics and redox kinetics.As a result,the Fe-Co₃O₄/Fe-Co₂N electrode material exhibited a high specific capacitance of 1595 F/g at a current density of 4 A/g and remain96.3 of the initial capacitance after 10000 cycles even at a high rate of 40 A/g.To extend the practicality of Fe-Co3O4/Fe-Co2N electrode materials,Fe-Co₃O₄/Fe-Co₂N nanoarrays were assembled into a symmetric solid-state supercapacitor device（Fe-Co₃O₄/Fe-Co₂N SSC）using a KOH gel electrolyte as two electrodes.The assembled Fe-Co₃O₄/Fe-Co₂N SSC can operate stably at a voltage window of 1.7 V.The specific capacitance of Fe-Co₃O₄/Fe-Co₂N SSC can reach 79 F/g at a current density of 0.5 A/g,and the energy density is 25.1 Wh/kg at a power density of 850 W/kg.and the capacity retention rate is 80%after 5000 cycles,presenting good practical potential of the Fe-Co₃O₄/Fe-Co₂N electrode materials in supercapacitor applications,This work provides new ideas for the strategy of supercapacitor electrode material synthesis.