熔融碳酸盐燃料电池电解质研究--NiO的溶解度和O2的还原行为

熔融碳酸盐燃料电池 (MCFC)具有发电效率高、环境友好以及能使用各种燃料等优点 ,但是 ,阴极的NiO溶解在碳酸盐中 ,并迁移到阳极被H2 还原成金属Ni ,造成电池短路 ,影响了使用寿命。为解决这一技术难点 ,延长MCFC的使用寿命 ,经优化计算得到了三元碱金属碳酸盐 (0 .474Li 0 .3 2 6Na 0 .2K )CO3 ,提出了用ICP法测定NiO在该碳酸盐中的溶解度 ,以及不同的气体组成和压力对NiO溶解度的影响 ;同时用电化学测试的方法对O2 在该电极体系的还原行为进行了研究。实验表明 ,NiO在该组成的碳酸盐中溶解度较小 ,而O2 的溶解度较大 ,这就减少了由于氧的扩散阻力造成的阴极极化 ,有利于加快氧的还原反应 ,因此该三元碱金属碳酸盐可作为熔融碳酸盐燃料电池适宜的电解质。

Studies on electrolyte for molten carbonate fuel cell--Solubility of NiO and reduction behavior of O2

Molten carbonate fuel cells (MCFC) show advantages on high power efficiency, environment friendly and availability of various fuels. However, NiO in its cathode is dissolved in carbonate electrolyte and turned into Ni 2 , and then is transferred to anode and reduced into Ni metal when Ni 2 ion reacts with H 2 there. This causes short circuit in MCFC and decrease its operating life. The ternary alkaline metal carbonate melt, (0.474 Li 0.326 Na 0.2 K) CO 3, was obtained by optimized calculation in order to deal with the technical obstacle and prolong the operating life of MCFC. The solubility of NiO in the carbonate melt mentioned above and the effects of various gas composition and pressure on NiO solubility were determined by means of ICP. The reduction behavior of O 2 at Au electrode in the carbonate melt was also investigated by means of electrochemical test. The results show that the solubility of NiO in the (0.474 Li 0.326 Na 0.2 K) CO 3 melt is low whereas that of O 2 is high. Therefore, the cathodic polarization caused by the diffusion resistance of O 2 is reduced and the reduction reaction of O 2 is accelerated. The (0.474 Li 0.326 Na 0.2 K) CO 3 carbonate melt is a suitable electrolyte for MCFC.