The Study On Promotion Of Durability And Dynamic Response Performance In PEMFC

The durability of proton exchange membrane fuel cell (PEMFC) is a major barrier for the commercialization. The dynamic response performance of a PEMFC significantly affects its durability and reliability. The life of PEMFC will shorten greatly under the working condition of vehicle, such as rapid variable load, start/stop frequently. Thus, development of the durability catalyst support and improvement of the dynamic performance of PEMFC have become the key for prolonging the PEMFC life.Firstly, as the carbon corrosion could be significantly accelerated, Graphite Nano-Fiber (GNF) with high stability was prepared from used carbon paper in PEMFC by a ball-milling method and adopted as the catalyst support. The electrochemical activity and stability of prepared Pt/GNF catalyst were investigated at80℃. Results show that Pt/GNF is significantly more stable than Pt/C by the constant potential oxidation and potential scan. Secondly, platinum nanoparticles are synthesized by alcohol reduction method using Nafion as a stabilizer. The mean size was estimated to be2-3nm for Pt/Nafion catalyst. Results show that the steady-state performance of Pt/Nafion catalyst is better than Pt/C. Pt/Nafion catalyst is significantly more stable than Pt/C by the potential scan. Pt/Nafion catalyst can avoid corrosion of carbon support and improve the Pt utilization.Finally, Pt/C-RuO2·xH2O catalyst is prepared by solegel method, and then assembled single cell. The stability of Pt/C-RuO2·xH2O catalyst were investigated under the condition of dynamic operations. The ON-OFF cycle, which determines the lifetime of a MEA, is one of the critical parameters for evaluating possible automotive application. In the current study, ON-OFF cycling tests were implemented with a single-cell until sudden cell failures.The average opencircuit voltage (OCV) of a PEMFC decreases with the Pt/C modified by RuO2·xH2O due to the synergistic effects of the interface between Pt and RuO2and the spillover of hydrogen. Therefore, decreasing the OCV improves the long-term durability of a PEMFC. RuO2·xH2O sprayed onto catalyst layers to promote PEMFC dynamic response performance. RuO2·xH2O is prepared by electrodeposition method at Pt/C electrode surface and assembled single cell. RuO2·xH2O is prepared by solegel method, and then sprayed onto catalyst layers. A10-cell stack is assembled using MEA with and without RuO2·xH2O. Single cell and stack are assembled using membrane electrode assembly (MEA) with and without RuO2·xH2O. Results show that the steady-state performance of the MEA with RuO2·xH2O is better than that in the MEA without RuO2·xH2O. A slower and more unstable dynamic response of the MEA without RuO2·xH2O is observed. Thus, RuO2·xH2O improves the dynamic response performance, indicating that RuO2·xH2O can buffer the voltage undershoot, improve the stability, and prolong the lifetime of the PEMFC.