Cu掺杂Ca_(3)Co_(4)O_(9+δ)中温固体氧化物燃料电池阴极材料

Cu-Doped Ca_(3)Co_(4)O_(9+δ)Cathode Materials for Intermediate-Temperature Solid Oxide Fuel Cells

采用固相法制备了Ca_(3)Co_(4-x)Cu_(x)O_(9+δ)(x=0,0.1,0.3,0.5)阴极材料,研究了Cu离子掺杂对材料的物相组成、电极微观形貌、电化学性能、热膨胀系数、电导率及单电池输出性能的影响。结果表明:在900℃的煅烧合成温度下,未掺杂与Cu掺杂量为x=0.1的生成产物具有相同单一物相晶体结构(JCPDS 21-0139),Cu掺杂使晶胞参数略有增加。掺杂量为x=0.1的阴极膜层呈现出最疏松多孔状态,有利于氧气在阴极的扩散传输,相应的极化阻抗最小(700℃时极化阻抗为0.85Ω·cm^(2),为未掺杂的42.9%),可以高效地催化氧气在阴极处的还原反应,而且具有最高的电子电导率(相比未掺杂的提高了1.6倍),提升了阴极反应过程中的电荷转移效率。采用Ca_(3)Co_(3.9)Cu_(0.1)O_(9+δ)为阴极的单电池输出性能明显优于其他组分作为阴极时的性能(700℃时功率密度峰值约为79 mW·cm^(-2),为未掺杂的1.9倍)。因此,Cu掺杂的Ca_(3)Co_(4)O_(9+δ)具有作为中温固体氧化物燃料电池阴极材料的应用潜力。

Ca_(3)Co_(4-x)Cu_(x)O_(9+δ)(x=0,0.1,0.3,0.5)cathode materials are prepared by the solid-state reaction.The influences of doping Cu ions on the phase composition,morphology,electrochemical performance,thermal expansion coefficient,electrical conductivity and single cell performance are investigated.The results show that at a calcination temperature of 900℃,the products of Cu-undoped and Cu-doped with x=0.1 have the same single-phase crystal structure(JCPDS 21-0139),and the Cu-doping increases the unit cell parameters slightly.The Ca3Co3.9Cu0.1O9+δcathode film presents the most loose and porous state,which is conducive to the diffusion and transport of oxygen in the cathode.The corresponding polarization impedance is the smallest(e.g.,the polarization impedance is 0.85Ω·cm^(2)at 700℃,and only 42.9%of the undoped one),which can efficiently catalyze the reduction reaction of oxygen at the cathode.Furthermore,the Ca_(3)Co_(3.9)Cu_(0.1)O_(9+δ)cathode has the highest electronic conductivity(1.6 times higher than that of the undoped one),which can promote the charge transfer efficiency during the cathode reaction.The output performance of the single cell with Ca_(3)Co_(3.9)Cu_(0.1)O_(9+δ)cathode is significantly higher than that of the cell with other cathodes(e.g.,the peak power density of about 79 mW·cm^(-2)at 700℃,1.9 times of the cell with undoped cathode).The Cu-doped Ca_(3)Co_(4)O_(9+δ)has great potential to be used as a cathode material for intermediate-temperature solid oxide fuel cells.