Study On The Performance Of Catalyst Ink For PEMFC

As an energy conversion device,the proton exchange membrane fuel cell converts chemical energy into electric energy.It has the advantages of low energy consumption,no pollution,green,and sustainability.Catalyst ink is the starting point of the preparation process of catalyst layers.The performance of ink directly determines the electrochemical performance of the catalyst layers.Therefore,improving the performance of catalyst slurry is a difficulty to overcome at the current stage.Catalyst,ionomer,and solvent are the three major components of catalyst ink.The interaction between them has an important impact on the performance of catalyst ink.In this paper,the effective ink dispersion process is selected first,and then based on the dispersion characteristics of the ionomer,the solvation of the ionomer is changed by changing the solvent composition and dispersion process characteristics,to study the influence of the ionomer dispersion state on ink performance.The results show that the homogenization method has the most efficient dispersion ability and can reduce the particle size of clusters in the catalyst slurry to 300～400 nm.Through rheological characterization,it is found that there are appropriate network structure strength and thixotropy in the ink prepared by the homogenization method and ball milling method,which is helpful to reduce the cracks on the catalyst and make the surface of the catalyst layer flatter.Using solvents with different water alcohol ratios to change the dispersion state of ionomer,it is found that in water/ethanol solvent,ionomer has the best dispersion state,which can make ionomer evenly dispersed in catalyst ink.The experimental results show that ethanol with a higher dielectric constant can make the surface potential of clusters in the ink higher（-68 m V）and more stable.The ultrasonic dispersion method was used to change the dispersion state of the ionomer.The results showed that ultrasonic action could further depolymerize the ionomer and make the ionomer enter the pores of catalyst clusters more fully.The catalyst layer prepared by the homogeneous method has better pore size distribution,optimizes the mass transfer capacity of the catalyst layer,and improves the fuel cell output voltage to 0.726 V at1000 m A·cm^-2,and the power density to1210 m W·cm^-2at 2000 m A·cm^-2.