| Aqueous zinc ion hybrid capacitor is composed of battery-type electrode and capacitive electrode.It not only considers the advantages of high energy density,high power density and long cycle life,but also has the advantages of higher ionic conductivity,lower cost,and higher safety.It is one of the most promising electrochemical energy storage devices.Electrospun carbon fibers have the advantages of high conductivity,stable physicochemical properties,and large specific surface area,which are one of the ideal electrode materials for electrochemical energy storage.However,it is still a great challenge to modulate and prepare electrospinning-derived carbon fibers to meet the kinetic requirements of zinc ion hybrid capacitors.Based on PAN-based electrospinning derived carbon,PAN/PVP blending strategy,ZnCl2 cross-linking/pore-making strategy and PAN/ZIF-8 collaborative strategy was used to regulate its microstructure,and the regulatory mechanism and electrochemical performance as positive electrode materials for zinc ion hybrid capacitors were explored.（1）Take the PAN/PVP blends strategy,according to the water thermal dissolution of bicomponent PVP mechanism,by adjusting the hydrothermal temperature,PAN/PVP proportion,specific surface area and pore structure of carbon fiber,finally get the PAN/PVP derived carbon（PVP/PANC）,The performance and energy storage mechanism of the zinc-ion hybrid capacitor are also studied.PVP-PANC-0.8 has a high specific surface area,many micropores and an appropriate amount of mesoporous.The high specific surface area and micropores provide sufficient space for charge storage,and the mesoporous structure guarantees the rapid transport of zinc ions.Therefore,the zinc ion hybrid capacitor with PVP-PANC-0.8 as the positive electrode material exhibited the specific capacity of 208 m A h g-1(current density of 0.5 A g-1)and good cycle stability（capacity retention rate of 72.25%after10 000 cycles）.Compared with pure PAN-based nanofibers,the electrochemical properties of the nanofibers have been significantly improved.（2）PAN/ZnCl2 three-dimensional cross-linked porous carbon nanofibers（3D-PANC）were prepared by ZnCl2 cross-linking/pore-building strategy,and three-dimensional cross-linked and graded porous structures were obtained by ZnCl2 cross-linking and pore-building.The three-dimensional crosslinking structure effectively improves the conductivity and stability,and the hierarchical porous structure provides a good ion transport channel and storage site,thus effectively improving the specific capacity and multiplier performance of zinc ion hybrid capacitors.The prepared zinc ion hybrid capacitor showed good specific capacitance(0.5 A g-1215 m A h g-1)and cycle stability(0.5 A g-1 current density,capacity retention rate reached 84.2%after 10000 cycles).In particular,the rate performance of 3D-PANC-10%//ZnZHS(capacity retention of 62.7%at 5 A g-1)is significantly better than that of PAN/PVP derived porous carbon nanofiber electrode(capacity retention of 49.5%at 5 A g-1).（3）Take the PAN/ZIF-8 cooperative strategy,the use of porous characteristics of ZIF-8and zinc attribute,the particle size by adjusting the ZIF-8 and adding quantity,PAN/ZIF-8derivative was successfully achieved porous carbon nanofibers（ZIF-8-PANC）,high electrical conductivity of carbon nanofibers improved ZIF-8 derivative problem of poor conductivity of carbon,The rich ZIF-8-derived carbon increases the specific surface area and porosity of carbon fiber.At a current density of 0.5 A g-1,the specific capacity of ZIF-8-PANC-250//ZnZHS can reach 240 m A h g-1,which is significantly better than that of 3D-PANC-10%//ZnZHS(0.5 A g-1 215 m A h g-1).In addition,ZIF-8-PANC-250//ZnZHS also exhibits excellent rate performance(84.3%capacity retention at 5 A g-1)and excellent cycle stability（91.4%capacity retention after 10,000 cycles）,which is also significantly better than the rate performance of3D-PANC-10%//ZnZHS(62.7%capacity retention at 5 A g-1)and cycle stability（84.2%capacity retention after 10,000 cycles）. |
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