制备了一种适用于中温固体氧化物燃料电池的新型两相复合电解质钐掺杂二氧化铈SDC-(Li/Na)₂SO₄. 使用XRD和SEM表征该复合电解质的物相结构和观察电解质片的截面形貌，交流阻抗法测量其400 ^oC ～ 700 ^oC的电导率. 结果表明，SDC-(Li/Na)₂SO₄由结晶相SDC和无定形相(Li/Na)₂SO₄组成. 在中温范围（500 ^oC ~ 700 ^oC）该复合电解质电导率比SDC显著增大并随温度升高呈三段变化：T<500 ^oC，表观离子传导活化能为1.28 eV；500 ^oC ～ 550 ^oC第二相硫酸盐融化，电导率激增；T≥550 ^oC，电导率又缓慢增加，活化能降为0.30 eV，与SDC和文献报道的SDC-(Li/Na)₂CO₃相比，其电导率均显著提高，如550 ^oC时SDC-(Li/Na)₂SO₄的电导率可达0.217 S·cm^-1，分别为SDC和SDC-(Li/Na)₂CO₃的25倍和3.2倍. 硫酸盐的熔融改变了离子在电解质中的传导机制，显著提高了SDC-(Li/Na)₂SO₄复合电解质的中温电导率.

A novel composite electrolyte SDC-(Li/Na)₂SO₄ was prepared for intermediate temperature solid oxide fuel cells (ITSOFC). The phase structure and cross-sectional morphology were examined by XRD and SEM, respectively, and the ionic conductivity was investigated by AC impedance in a temperature range of 400 ^oC ~ 700 ^oC in air. It was found that the composite electrolyte was composed of two phases: crystal SDC and amorphous (Li/Na)₂SO₄. The conductivity of the composite electrolyte was significantly larger than that of SDC at intermediate temperatures (550 ^oC ~ 700 ^oC) and increased with temperature in three stages: 1) T<500 ^oC, the apparent activation energy of ionic transport was 1.28 eV; 2) In the range of 500 ^oC ～ 550 ^oC, the ionic conductivity rapidly increased due to the melting of sulfate; 3) T>550 ^oC, the conductivity slowly raised with temperature, the activation energy decreased significantly to 0.30 eV, and the values of the conductivity of SDC-(Li/Na)₂SO₄ were notabily higher than those of SDC and previously reported SDC-(Li/Na)₂CO₃. For example, the conductivity of SDC-(Li/Na)₂SO₄ was 0.217 S·cm^-1 at 550 ^oC, which was 25 times higher than that of SDC and 3.2 times higher than that of SDC-(Li/Na)₂CO₃. The results indicate that the ionic conducting mechanism changes in composite electrolyte due to the melting of the sulfate second phase, and the diffusion and transmission of ions are accelerated.