Preparation And Application Of Bifunctional Catalyst For Zinc-air Flow Battery

Energy is the foundation and driving force for the development of human society.At present,73%of energy comes from fossil fuels such as oil,coal and natural gas.However,fossil energy reserves are limited and non-renewable.Renewable energy use technology is an urgent matter.Solar energy,wind energy,and tidal energy all have abundant resources.In recent years,the total installed capacity of renewable energy such as wind energy,solar energy,and tidal energy has been increasing.However,due to instability and discontinuity of power generation,there are some problems such as abandonment of wind and disposal of light.From a long-term point of view,large-scale energy storage may be the most effective and economical solution to the unstable and discontinuous of renewable energy,and it is also an important means to increase the utilization rate of renewable energy.Zinc air flow batteries have become one of the first choices for large-scale high-efficiency energy storage devices due to their advantages such as high energy density,good safety,and low price.In the zinc-air flow battery,the reaction kinetics of anode oxygen reduction reaction and oxygen evolution reaction is slow,and the anode oxygen reduction/evolution catalyst plays a decisive role.It is a key and difficult point to develop a stable and efficient catalyst.This project aims to provide a feasible solution for constructing a highly efficient zinc-air flow battery by preparing a highly efficient,inexpensive,and stable oxygen reduction/evolution bifunctional catalyst that reduces battery cost and improves battery performance.The main content of this article is as follows:1)Using ordinary carbon fiber paper(CFP)as a carrier,after strong acid treatment,defects are generated.Then by hydrothermal and high temperature pyrolysis,an efficient unitary oxygen electrode doped with amorphous NiSx-FeOy was prepared on sulfur-doped carbon fiber paper(SCFP).The prepared NiSx-FeOy/SCFP catalyst has the best performance.The OER only needs 0.37 V overpotential to reach the current density of 10 mA cm-2,and ORR has a half-wave equivalent to commercial 20 wt%Pt/C.The NiSx-FeOy/SCFP was directly used as the positive electrode of the zinc-air flow battery and assembled the zinc-air flow battery,exhibiting high charge and discharge performance and vigorously operating for 110 hours without degradation of performance.2)Using Toray carbon fiber paper as a carrier,2-amino-5-mercapto-1,3,4-thiadiazole(AMT)was polymerized onto carbon fibers using an electropolymerization method.After high temperature pyrolysis,it is carbonized and activated to obtain PAMT/CFP.The obtained PAMT/CFP can be directly used as the anode of the zinc-air flow battery.The OER needs only 1.68 V to reach the current density of 10 mA cm-2,and the ORR is also the best.The ORR half-wave potential is about 0.68V,so providing a new idea for the research of the bifunctional catalyst.3)Using a Sonogashira-Hagihara coupling reaction to synthesize conjugated microporous polymer(CMP)with a structure and composition that is rich in nitrogen,sulfur and other elements.A conjugated microporous polymer is used as a precursor to introduce high-density,highly-dispersed transition metal atoms to prepare nitrogen-,sulfur-,and transition-metal-doped carbon-based catalytic materials.At the same time,rich oxygen reduction reaction and oxygen evolution reaction active sites are constructed.At this point,the ORR starting point is only 0.88 V,the half-wave potential is 0.78 V,and the voltage corresponding to the current density of 10 mA cm-2 is 1.68 V.We studied the interaction between N,S,and transition metals such as Fe and Ni to design a bifunctional catalyst with excellent performance.4)In this study,carbon fiber paper was used as a carrier,and hydrothermal and high temperature pyrolysis methods were used to prepare Fe,Ni co-doped bifunctional self-supporting oxygen electrodes on sulfur-doped carbon fiber paper(SCFP),and high-efficiency and stable zinc-Air flow battery was assembled.Then we use Toray carbon fiber paper as a carrier,and use electropolymerization and high temperature pyrolysis to polymerize AMT on the carbon fiber surface to prepare a non-metal bifunctional oxygen electrode.Finally,we synthesize conjugated microporous polymers using Sonogashira-Hagihara coupling reaction with organic monomers rich in nitrogen,sulfur and other elements.Directional introduction of excessive metal atoms into conjugated microporous polymers to prepare nitrogen-,sulfur-,and transition-metal-doped carbon-based catalytic materials...