Study On Technology Of Novel Air-cooled Self-humidifying PEMFC

In the last two to three decades, Proton Exchange Membrane fuel cells (PEMFC) have aroused so many interests in the areas of transportation and telecommunication. Performance and economy of the fuel cells are both important for the final consumer. Unfortunately, state-of-the-art fuel cells could not satisfy all the application scenarios. The self-humidifying operation of PEMFC is one of the most promising application technology. Recently, many research groups attempt to remove the externally humidifying unit from PEMFC system by endowing the proton exchange membrane with self-humidifying ability. Air-cooled self-humidifying proton exchange membrane fuel cell with simplicity in structure is very suitable for power sources which are lower than 10kW.A novel method of high pressure and temperature-cape casting was adapted to prepare four kinds of self-humidifying proton exchange membrane with pt adding to them. XRD,TGA, FTIR, SEM, XPS, etc methods were adapted to characterized the performance of the cell which is assembly in this research work. The experimental data show that membrane of Pt-PSFA has an excellent mechanical strength, steady in chemical property, and high proton electrical conductivity. Under the operation of dry H2/air gas, it can give electrical power with self-humidifying. The maximum power Pmax is 520mW-cm-2, its electrical capacity is larger than membrane of Nafion112. The self-humidifying proton exchange membrane also show a stability in its performance in a long time testing, but its durability is not as good as the composite membrane, the gas permeability of the membrane has been increased much after 1000hour testing.A newly developed type of thermoforming CCM-MEA preparation technique was used to prepare a thin membrane of PEMFC with its proton membrane as Nafionlll, it can meet the operation condition of self-humidifying requirement. it was also compared with the traditional GDL-MEA technique. It electrical capacity increases approximately 20%. From the comparisons with the commercial PTFE enhanced by MEA it can be concluded that:the electrical capacity of the membrane prepared by CCM-MEA approach the capacity of commercial MEA, it indicate that CCM-MEA is a candidate technique to increase the capacity of self-humidifying proton membrane enhanced by MEA. The working conditions and water management tasks of anode and cathode gas diffusion electrodes (GDE) are quite different in self-humidifying PEMFC, so it’s necessary to use asymmetric GDE to fulfill the different water management requirements in anode and cathode, which were seldom reported in literatures. In this article, influences of asymmetric GDEs on PEMFC performance with different thickness carbon papers and different PTFE loading are studied. Experimental results indicate that, increase anode carbon paper thickness and decrease that of cathode will increase fuel cell performances, furthermore, enhance anode GDE hydrophobicity and reduce that of cathode will benefit in anode water content and cathode flooding preventing, which will in turn enhance fuel cell performances. In this study, fuel cell with asymmetric anode GDE with 60%PTFE and cathode with 20%PTFE shows 5%power higher than symmetric 40%PTFE GDEs and 9.16%higher than commercial SIGRACET(?) GDEs.Water management is of great importance to maintain performance and durability of PEMFCs. This article presents a novel PEMFC with a humidification area in the membrane electrode assembly (MEA) of each cell, in which the moisture of the cathode exhaust gas could transfer through the membrane to humidify anode or cathode dry gas. Based on the results of membrane humidifying test and single cell test, we can draw the below conclusion: Membrane electrode (MEA) with humidifying zone could effectively humidify reaction gas, wet air humidity from 0%to 62.2%.When the cell operating temperature is high (60℃), the performance of the single cell in the hydrogen humidifying and air humidifying is higher than the performance of no humidifying.And the single cell discharges under the conditions of 0.5V, hydrogen humidifying and air humidifying can be both stable.This research offers a novelty approach for the water and heat management in the fuel cell. It combine the heat absorb feature of in store hydrogen material with the character of heat give off during the fuel cell operation. It also benefits for stable self humidifying operation of fuel cell. It satisfactorily couples the in store hydrogen material with the fuel cell by utilizing the heat of each. This work opens a new approach to minimize the volume of fuel cell, increase the density of energy and power capacity.