Study On Mechanisms Of Degradation And Regeneration In DMFC Durability

Direct methanol fuel cell (DMFC) has lots of advantage such as convenient fuel storage, low operating temperature and simple structure etc., which is considered as a type of fuel cell with broader business prospects in electronic products, automobile power system and small power generation assembly. However, the commercialization of DMFCs is seriously restricted by its relatively low performance and poor durability. Based on analyzing the regeneration and non-regeneration attenuation factors of the cell’s performance, this paper studies on the improvement of porous electrode preparation, the choice of the methanol fuel additive, the optimization of long-time running condition and the introduction of the performance renewable method, in order to realize the promotion of DMFCs performance and durability.According to the reseach on the long-time running durability test, after long-time running, the loss of Ru at anode, the agglomeration of catalyst particle and the destruction of porous electrode structure are the non-regeneration attenuation factors; water flooding at cathode, Pt catalyst’s surface oxidation and the prisoning of methanol to anode were regeneration attenuation factors. The change of temperature, the supply of oxygen and methanol and on-off strategy would influence the cell’s durability, and with operation optimization such as N2protection for platinum catalyst, methanol permeability velocity restrain, temperature fluctuation control and cathode mass transfer channel flow dredging, the durability rose.The optimization of porous electrode preparation and the introduction of anode methanol additive were used to improve the DMFCs performance and durability. Methanol crossover resisting layer can limit methanol crossover,3D hot-press method can reduce concentration polarization and hydrophilic anode diffusion layer can improve the anode methanol transmission; Surfactant added in methanol can accelerate the transport of CO2and H2O2can inhibit the COaas poison phenomenon at anode in the process of methanol electro-oxidation. With the above methods, the cell’s performances were optimized and the power density reached262mW/cm2.Cell’s durabliltiy reasons in long-time running were studied, which included the process of the product jaming pore structure to hinder mass transfer, the reunite and loss of catalyst and the effect of temporary deactivation to electrocatalysis and membrane electrode structure damage resulting in the cell internal resistance and the methanol permeability increasing. Performance regeneration methods such as the reduction of Pt surface oxidation, supplement regeneration of membrane proton erosion and cathode mass transfer channel flow dredging were introduced into durability test in order to recover cell’s performance. Through the optimization of cell’s condition and the introduction of performance regeneration method, the single running times reached119hours and the total time of durability running rose up to2400hours, under the condition that the power density was80mW/cm2and the decay rate (τ) was8%.