熔融碳酸盐燃料电池ZnO/NiO阴极稳定性及电化学性能研究

以ZnO作添加物,采用流延成型法制备了ZnO/Ni复合阴极,研究其微观形貌和相组成,并应用交流阻抗谱研究了ZnO/NiO复合阴极在(Li0.62K0.38)2CO3低共熔盐中的稳定性和电化学性能.结果表明,ZnO/Ni复合阴极和Ni阴极具有基本相近的表面形貌、空隙率和孔径尺寸.ZnO的添加能显著降低NiO在熔盐中的溶解度,其中,2mol%ZnO/NiO复合阴极的NiO溶解度比纯NiO阴极的约低1个数量级,并具有较低的电荷传递电阻(接近于纯NiO值),可望成为MCFC一种很有前景的阴极材料.

Stability and Electrochemical Performance of NiO Cathode Modified by ZnO Additive for MCFC in Molten Carbonates

The ZnO/Ni composite cathode was fabricated by tape-casting method, which microstructures and phases were studied. The electrochemical behaviors of ZnO impregnated NiO cathodes were also evaluated in molten 62 mol%Li_2CO_3+(38 mol%) K_2CO_3eutectic at 650 ℃ by electrochemical impedance spectroscopy (EIS) as a function of ZnO content and immersion time. The ZnO impregnated nickel cathodes showed the similar porosity, pore size and morphology to the reference nickel cathode. The stability tests of ZnO impregnated NiO cathodes showed that the ZnO additive could dramatically reduce the solubility of NiO in a eutectic carbonate mixture under the standard cathode gas condition. The cathode material having 2 mol.% of ZnO showed a very low dissolution and a good catalytic efficiency close to the NiO value and would be able to adapt as alternative cathode materials for MCFCs.