Study On Supercapacitors Based On Heterointerface Materials And Self-Charging Power System

Supercapacitors（SC）involving the surface/interface reaction,as a typical representative of the next generation of energy storage devices,feature the advantages of high-power density,fast charge-discharge capability and long cycle life,thus showing great application prospects in the future energy storage and conversion fields.However,the sluggish ion mass transfer and electron transport kinetics seriously limit the efficient surface/interface charges storage.Furthermore,the frequent charging and power supply of traditional SC further restricts their practical application.In this thesis,we have proposed to routes and stratages for the design and develop of a series of highly active and stable heterostructure composite materials based on conductive flexible carbon cloth（CC）,regulating the surface pore structure,active components and dimensional structure,enhancing the ion and electron transfer kinetics,as well as finally improving the energy storage performance.Meanwhile,we have also designed and fabricated novel piezo-film and high-performance triboelectric nanogenerators（TENG）,and developed self-charging supercapacitors power cell（SCSPC）and self-charging power systems（SCPS）to achieve efficient energy harvesting and storage.The main results as follows:1.Developing N-C@Ni₃N/Co₃N//N-C supercapacitor with high energy density and long cycle capability:The porous N-C@Ni₃N/Co₃N heterostructure was constructed by electrodeposition and heat treatment on the flexible CC substrate.The composite material has abundant pore structure,which provides a convenient channel for electrolyte ion diffusion,thus improving the ion mass transfer kinetics.It also has a clear heterogeneous interface,which reconstructs the interfacial electron configuration and optimizes the electron transport dynamics.It also has well-defined heterointerface that reconstructs the interfacial electron configuration and optimizes the electron transport kinetics.Meanwhile,N-C nanocoating not only provides a stable frame structure for the robust and uniform growth of Ni₃N/Co₃N heterostructure,but also effectively regulates the electronic structure states,improving the strong coupling interaction between CC and Ni₃N/Co₃N,and achieving the excellent electrochemical stability.In a three-electrode system,N-C@Ni₃N/Co₃N exhibits high capacity(3773m F cm^-2@1 m A cm^-2),outstanding rate performance(85.7%@25 m A cm^-2),and well cyclic stability（85.6%@5000 cycles）.Importantly,the N-C@Ni₃N/Co₃N//N-C device assembled by N-C@Ni₃N/Co₃N and N-C achieves high energy density(64.1 Wh kg^-1@752 W kg^-1)and long-term cycle stability（92.6%@5000 cycles）.2.Developing highly integrated self-charging supercapacitors to realize the all-in-one of energy harvesting/storage:The homologous Ni Co P/Ni Co N heterostructure was constructed by hydrothermal and phosphonitridation on the flexible CC substrate.The composite material integrates the distinct advantages of optimized electronic structure and strong synergistic effect on heterointerface to realize efficient electron transport and fast reaction kinetics.In a three-electrode system,Ni Co P/Ni Co N achieved high capacitance of 3544 m F cm^-2 at 1m A cm^-2 current density and excellent cycle stability（84.4%@5000 cycles）.The P（VDF-Tr FE）/BTO piezo-film was prepared by spin coating-polarization,which realized high open circuit voltage and short circuit current.Importantly,we propose a novel SCSPC composed of Ni Co P/Ni Co N heterostructure as positive electrode and active carbon as negative electrode and P（VDF-Tr FE）/BTO piezo-film as separator.Benefiting from heterointerface engineering and piezoelectric effect,SCSPC simultaneously exhibits excellent energy storage performance(62.1 Wh kg^-1@850 W kg^-1)and superior self-charging characteristics（132 m V@155s）.3.Developing self-charging energy systems toward efficient energy harvesting and storage:Dual redox active sites Ni₂P/NiSe₂ heterostructure is homogeneously inlaid on N-C（N-C@Ni₂P/NiSe₂）via electrodeposition,hydrothermal and phosphoselenization on the flexible CC,which achieves the maximum exposure of active sites and prevents the aggregation of nanoparticles.The composite material features high activity dual redox sites,well-defined heterointerface,and high conductivity support,which facilitates high electrochemical reaction efficiency,accelerated reaction kinetics,and enhanced electrochemical stability,thus achieving high capacitance(4660 m F cm^-2@1 m A cm^-2)and excellent stability（88.7%@5000cycles）.Meanwhile,the solid-state asymmetric SC device（SASD）assembled by N-C@Ni₂P/NiSe₂ and N-C exhibits high energy density(60.4Wh kg^-1@1598.8 W kg^-1).Moreover,the developed TENG based on PTFE and Cu electrodes has high output performance,which achieves efficient energy harvesting.The SASD is integrated with TENG as a SCPS,achieving high self-charging voltage（3.8 V@40 s）and cycle stability（99%@60 cycles）.