Study On The Electrochemical And Cold Start Characteristics Of Electrospun Catalyst Layer For Fuel Cell

Catalyst layer(CL)is the key component of the fuel cell,facing the requirements of reducing cost and improving performance.Electrospun CL has become a research hotspot due to its high performance and durability,but the mechanism of its performance improvement and aging is not well understood.Meanwhile,the research on cold start characteristics of electrospun CL is absent.Therefore,the purpose of this paper is to reveal the performance improvement,aging mechanism and cold start capability and durability of electrospun CL.Firstly,we disclosed the structural characteristics of the electrospun CL by studying the microscopic morphology.The pore size distribution of the electrospun CL and the commercial CL was characterized by N2 adsorption and desorption method.We found that electrospun CL can expose more pores with a diameter of 2 to 7 nm which are from the inside of the carbon support.Elements distribution of single nanofiber cross-section of electrospun CL were characterized by Electron Energy Disperse Spectroscopy And we found that platinum was concentrated in the center of the fiber cross-section.Then,we revealed the mechanism of performance improvement and aging of electrospun CL by studying the electric double-layer interface and ionomer coverage.The electrospun CL has a larger double-layer interface of platinum and ionomer as well as platinum and water,which improving the three-phase interface.Meanwhile,it has a lower ionomer coverage on platinum surface than commercial CL,which is beneficial for reducing the local transfer resistance of O2 transport.During load cycles,the platinum surface of electrospun CL that not covered by the ionomer suffered more severe degradation.And the ionomer coverage on the platinum surface is increased,resulting in decreasing of reaction interface and the increasing of the mass transfer.Finally,we studied the cold start capability and durability of electrospun CL.Compared with commercial CL,electrospun CL has higher cold start capability because the more microspores in the nanofiber can reduce the freezing probability of the super cooling water.Meanwhile,electrospun CL has higher cold start durability of electrospun CL because the nanofibers have stronger mechanical stability than the particle stacking structure,which is beneficial for withstanding the freezing-thaw stress.This study reveals the mechanism of performance improving and aging of the electrospun CL from the perspective of electrochemical interface and ionomer coverage.At the same time,the cold-start capability and durability are studied.