关键词: 磺化聚芳醚砜酮, 硫酸化二氧化锡, 纳米粒子, 有机无机复合质子交换膜, 直接甲醇燃料电池

Abstract:

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.

Key words: sulfonated poly(phthalazinone ether sulfone ketone), sulfated tin dioxide, nanoparticles, organic-inorganic composite proton exchange membrane, direct methanol fuel cell