粉末粒径对等离子喷涂固体氧化物燃料电池阳极微观结构及性能的影响

Effect of Powder Particle Size on Anode Microstructure and Performance for Plasma-Sprayed Solid Oxide Fuel Cell

作为固体氧化物燃料电池阳极材料,选用NiO/Gd_(0.2)Ce_(0.8)O_(1.9)(GDC)替换传统NiO/Y_(0.16)Zr_(0.92)O_(2.08),其可有效扩展三相反应界面,提高电池性能。采用大气等离子喷涂技术,通过调控NiO/GDC团聚粉末粒径,研究阳极微观结构演变及对电池性能的影响。结果表明:粉末粒径影响粉末的熔化程度,当d50=24.7μm的小粒径粉末熔化充分时,涂层中会暴露更多的GDC,增加反应活性位点;d50=45.2μm的大粒径粉末熔化不充分时,堆叠产生的间隙会造成涂层中裂纹和孔洞增多,表现出更大的气通量,泄漏率为14.8×10^(-6)cm^(4)·gf^(-1)·s^(-1);小粒径和大粒径粉末阳极形成的单电池输出峰功率密度接近,在800℃时分别达到1 158.46和1 147.0 mW·cm^(-2)。阻抗谱拟合结果揭示了阳极界面电荷转移和气体传输能力的差异。通过分析粉末粒径对电化学性能的作用机理可知,小粒径粉末阳极具有更多界面活性位点而表现出更快的电荷转移速度,大粒径粉末阳极具有优异的透气性,能透过更多燃料而有效激发活性位点。因此,在大小粒径粉末阳极上形成的电池几乎表现出相同的电化学性能。

As a solid oxide fuel cell anode material,NiO/Gd_(0.2)Ce_(0.8)O_(1.9)(GDC)is used to replace the conventional NiO/Y_(0.16)Zr_(0.92)O_(2.08),which can effectively extend the triple-phase boundaries and improve the cell performance.In this paper,the evolution of anode microstructure and its effect on cell performance is studied by regulating the particle size of NiO/GDC agglomerated powder via atmospheric plasma spraying technique.The results show that the powder particle size affects the melting degree,and the small particle size powder melts sufficiently so that more GDC is exposed in the coating to increase the reactive sites.The large particle size powder melts insufficiently,and particle stacking creates gaps leading to more cracks and pores in the coating,thus exhibiting a larger gas flux with a leakage rate of 14.8×10^(-6) cm^(4)·gf^(-1)·s^(-1).The output peak power density of single cells formed by anode with small and large particle sizes is close to each other,reaching 1158.46 and 1147.0 mW·cm^(-2) at 800℃.The impedance spectrum fitting reveals the difference in interfacial charge transfer and gas transport capability of the anodes.By analyzing the mechanism of powder particle size on electrochemical performance,it was found that the small-particle-size anode has more interfacial active sites and shows a faster charge transfer rate,while the largeparticle-size anode has excellent gas permeability and can pass through more fuel to effectively excite active sites.Therefore,the two cells exhibit almost the same electrochemical performance.