Preparation And Electrochemical Performance Of Field-assisted Zinc-air Battery Cathode Catalyst

Zinc-air battery as one of the new generation of battery system,its theoretical specific energy is as high as 1086 Wh kg^-1,specific capacity up to 820 Ah kg^-1,which is about 5times that of the current commercial lithium-ion battery(200～250 Wh kg^-1),and zinc has the advantages of environmental friendliness,resource abundance,low cost and good safety,so it has attracted much attention.However,the system is not yet perfect,and there are several problems that need to be solved,one of which is the high overpotential.Due to its slow reaction kinetic process,zinc-air battery will produce a large charging voltage when charging,usually up to 2 V,far beyond the theoretical voltage of 1.65 V,so it is extremely necessary to reduce the overpotential of zinc-air batteries,and the most common solution to this problem is to use a photocathode to assist zinc-air battery charging.However,the problem of rapid recombination of photogenerated carriers hinders the further development of photo-assisted zinc-air batteries.In this regard,we conducted the following studies:A novel pyroelectric effect synergistic light material was designed,and vinylidene fluoride-trifluoroethylene-chlorofluoroethylene（PVTC）was coated with vinylidene fluoride-trifluoroethylene-chlorofluoroethylene（PVTC）on a carbon spherical shell（HCN）by hydrothermal method,and Cd S（HCN@PVTC@Cd S）was grown.The synthesized HCN diameter is 300 nm,the thickness of the coated PVTC is 16 nm,the diameter of the loaded Cd S is 85 nm,under the illumination,HCN absorbs light as a heat source,PVTC as a pyroelectric material,the internal positive and negative charge centers are separated when heated,spontaneous polarization occurs,and a built-in electric field is generated,and the built-in electric field acts on the photogenerated electron holes generated by Cd S,thereby improving the separation efficiency of photogenerated electron holes.Through ultraviolet and PL spectroscopy combined with finite element simulation,it is proved that the pyroelectric effect of HCN@PVTC@Cd S can well cooperate with illumination to reduce the recombination rate of photogenerated electron holes and increase the utilization rate of light energy.With HCN@PVTC@CdS as the photocathode of light-assisted zinc-air batteries,the pyroelectric effect and light can effectively promote the reaction kinetics and reduce the reaction overpotential.The electrochemical performance of pyroelectric photo-assisted zinc-air batteries was tested,and the electrochemical performance was superior,and the relationship between temperature change（T）and overpotential of pyroelectric materials was further studied,and the results showed that the larger theΔT,the smaller the potential and the inverse relationship.Under the action of pyroelectric effect and synergistic illumination,the battery has a high discharge potential of 1.33 V,a low charging potential of 1.5 V and good cycle stability.This multi-assist technology with built-in electric and light fields paves the way for the development of high-performance zinc-air batteries and other energy storage systems.