硫酸化SnO2/SPPESK复合质子交换膜的制备及燃料电池性能

非氟聚合物磺化聚芳醚砜酮（SPPESK）具有甲醇渗透率低、化学、热稳定性高等优点，但其高的电导率需通过提高磺化度获得，导致膜因过度溶胀而失去尺寸稳定性。添加无机纳米颗粒可以有效提高膜性能，但因其表面缺少功能化基团，导致颗粒有机相容性差，阻醇性能和质子传导率不易同时提高。硫酸化改性的纳米颗粒因其表面具有酸性位点和硫酸基团，能够有效克服这一问题。本文制备表面硫酸化改性的SnO₂（SSnO₂）纳米颗粒并引入SPPESK基质制备有机无机复合质子交换膜。当SSnO₂含量不大于7.5%时，纳米颗粒具有良好的有机相容性，可均匀分散于聚合物基质。SSnO₂含量为7.5%时，80℃下复合膜吸水率（19.6%）比SPPESK原膜提高19%，接近Nafion115。颗粒诱导膜内离子簇的聚集扩大，降低了质子的传导阻力，质子传导率分别比SPPESK原膜和Nafion115膜提高48%和30%。同时，纳米颗粒增大了甲醇传递空间位阻，甲醇渗透率较SPPESK原膜和Nafion115膜分别降低46%和71%。直接甲醇燃料电池0.5V处功率密度分别比SPPESK原膜和Nafion115膜高205%和50%。

Preparation and fuel cell performance of sulfated SnO2/SPPESK composite proton exchange membranes

Sulfonated poly(phthalazinone ether sulfone ketone)(SPPESK), a novel non-fluorinated polymer, possesses the advantages of low methanol permeability, high chemical and thermal stability, but the obtained high conductivity needs high degree of sulfonation, resulting in the loss of membrane dimensional stability due to the excessive swelling. The introduction of inorganic nanoparticles can effectively improve the membrane performance. However, due to the lack of functional groups on the surface, the inorganic particles often show poor organic compatibility. Besides, the membrane’s anti-methanol permeability and proton conductivity cannot be easily improved simultaneously. The sulfated nanoparticles with acidic sites and sulfate groups on the surface can effectively overcome this problem. The SPPESK based composite proton exchange membranes were prepared by doping sulfated SnO₂ (SSnO₂) nanoparticles. The SSnO₂ showed good organic compatibility when the content was not more than 7.5%. Compared with the pristine membrane, the composite membrane containing 7.5% SSnO₂ showed higher water uptake (improved by 19%) at 80℃ in, and the swelling ratio (19.6%) was close to that of Nafion115. The nanoparticles induced the aggregation and expansion of the ion clusters in the membrane, which led to the low-resistance transfer of protons. Compared with pristine SPPESK and Nafion115, the composite membrane showed conductivity increases of 48% and 30% at 80℃, methanol permeability reductions of 46% and 71% and power density enhancements at 0.5V of direct methanol fuel cell of 205% and 50%, respectively.