Assembly And Electrochemical Properties Of Flexible Supercapacitors Based On Nano Nickel Cobalt Compound Prepared By Template Method

The increasing demand for flexibly and wearably microelectronic devices in modern life has promoted the development of corresponding flexible,intelligent and safe energy storage devices.Flexible supercapacitors(SCs)possess light-weight,excellent flexibility,high power density,outstanding cycle stability and safety,which are considered as the promising candidates.So far,most SCs are still unable to meet practical applications due to their low energy density and flexibility.It is still a big challenge to prepare the flexible SCs with high specific capacitance and energy density.Carbon nanotube(CNT)film can be used as the base material of flexible supercapacitors,but its low capacitance and energy density still affect the further application.SC with high specific capacitance and high energy density can be achieved by preparing high-performance electrode or assemble asymmetric devices.In this paper,NiCo2O4,CNT@NiCo₂O₄ and CNT@NiCo₂Se₄ were fabricated using hyperbranched polymer as a template,and the performance of flexible SC assembled by CNT@NiCo₂O₄ or CNT@NiCo₂Se₄ was studied.The detailed research content is as follows.(1)NiCo₂O₄ were prepared by hyperbranched polymers as template,and the electrochemistry of NiCo₂O₄ was researched.First,NiCo₂O₄ were successfully prepared using epoxy-terminated hyperbranched polymer(CHP),hydroxyl-terminated hyperbranched polymer(H102),and carboxyl-terminated hyperbranched polymer(CHP)as template,respectively.NiCo₂O₄ prepared with EHP as the template had the highest specific capacitance.NiCo₂O₄ prepared by EHP as a template possessed the highest specific capacitance.The effect of the molar ratio of Cl^-and NO3^-on the specific capacitance of NiCo₂O₄ was studied using the three-electrode system and BET specific surface area test when EHP was used as a template.It is found that the specific capacitance of NiCo₂O₄ increases first and then decreases as the ratio of Cl^-and NO3^-increases.The maximum value was appeared when Cl^-:NO3^-=0.5.Finally,FT-IR,XRD and TG were used to study the reaction mechanism of preparing NiCo₂O₄ using EHP as the reactive template.(2)CNT@NiCo₂O₄ was prepared using EHP as template,and two pieces CNT@NiCo₂O₄ films were used to construct flexible symmetrical device.First,the porous CNT@NiCo₂O₄ was prepared in-situ on the untreated CNT film using EHP as a template,the electrode has a specific capacitance of 281.7 F cm^-3,and has a higher specific surface area and more excellent electrochemical stability than NiCo2O4,which proves that CNT as a substrate is conducive to a significant increase in capacitance and stable performance of active material.The assembled symmetrical supercapacitor based on CNT@NiCo₂O₄ has a capacitance of 23.3 F cm^-3,good cycle performance,excellent bending performance and an energy density of 3.2 m Wh cm^-3.(3)CNT@NiCo₂Se₄ was prepared using EHP as template,and flexible asymmetric devices was constructed by CNT@NiCo₂Se₄.First,CNT@NiCo₂O₄ was prepared in-situ on the CNT film using EHP as a template,then CNT@NiCo₂O₄ was selenized to prepare CNT@NiCo₂Se₄ with better performance as a positive electrode for an asymmetric device.CNT@PPy as negative electrode with high stability and high capacitance was prepared by adjusting precursor concentration and deposition time.Then CNT@NiCo₂Se₄//CNT@PPy asymmetric supercapacitor was designed and assembled.The device with a voltage window of 1.5 V has a capacitance of 50.56 F cm^-3,and an energy density of 15.7 m Wh cm^-3,which also showing excellent electrochemical stability.