Preparation And Research Of High Performance Cathode Catalyst For Rechargeable Zinc-air Battery

Due to the high power density,high energy conversion efficiency and lack of pollution,the use of regenerative zinc–air batteries as clean and efficient energy conversion and storage technologies can,to a great extent,mitigate the worldwide energy and ecological crises caused by the immoderate consumption of fossil fuels.In this context,Pt and Ir alloys or oxides still represent the most efficient OER and ORR catalysts.Nevertheless,challenges such as their high cost,scarcity and low stability still limit the large-scale commercialization of these devices.Therefore,the development of efficient and cost-effective bifunctional catalysts for OER and ORR is of great scientific and technological importance.At present,the design and preparation of the cathode catalytic materials of excellent zinc-air cell are mainly focused on the morphology control,pore structure design and active site design of the catalyst.Therefore,in this paper,Subject involves the following two specific content.First,by using semi-closed carbonization method assisted by eutectic salt,according to the template action of ZnCl₂ and KCl and nano-scoped effect,catalyst of porous nitrogen-doped Fe/N/C with high performance were produced.The additive proportion of salt template and carbonization temperature were also explored.The test results of SEM?TEM?BET?CV etc showed that when ZnCl₂ and KCl the ratio of 1:1,carbonization temperature is 800?,the catalyst has excellent pore structure of three-dimensional transport channel.The specific surface area increase to 1120 cm^-2g^-1,it greatly increases the active sites of catalyst in the three-phase interface.The results of the XPS shows that the catalyst has high nitrogen content?11.3%?,the degree of graphitization of this catalyst is better than the catalyst with other five kinds of salt template ratio or different carbonization temperature.In ORR tests,this prepared catalyst exhibits a half-wave potential of 0.892 V in alkaline media,which exhibits a 32mV positive shift in the half-wave potential and much higher diffusion-limited geometric current comparing to the commercial Pt/C.Above results demonstrate that the catalyst have good application prospects in alkaline media.Besides,in order to inquire the optimum mixing proportion and synergistic effect,the obtained Fe-Ni₂P nanosheet catalyst material was characterized by physical characterization and mixed with the above Fe/N/C catalyst with different proportions.The OER physical characterizations show that the obtained Fe-Ni₂P nanosheet catalyst presents the orderly and uniform nano-porous layer structure.After calcined at350?,the XRD results indicate that the Ni-Fe LDH are doped with phosphorus.The characterization of EDX demonstrates that the ratio of Ni and P is 2:1and the ratio of Ni and Fe is 3:4.This also demonstrates the obtained catalyst was Fe-Ni₂P nano-porous layer material.Then we explores the impact of the addition amount of Fe/N/C material on OER performance and the impact of the addition amount of Fe-Ni₂P material on ORR performance.Notably,The results demonstrate that the maximum performance of OER and ORR was achieved when the ratio of Fe/N/C and Fe-Ni₂P material is 1:1,the obtained material was named as Fe/N/C@50%Fe-Ni₂P catalyst.Then the Fe/N/C@50%Fe-Ni₂P bifunctional sample was characterized by charge-discharge tests and cyclic measurement.Test results show that the total overpotential of Charge and discharge is lower than that of Pt/C-IrO₂.The overall energy exchange efficiency and stability are higher than noble Pt/C-IrO₂ catalyst,which provide a new possibilities for the future commercialization of this catalyst.