CVD法制备质子交换膜燃料电池用炭纤维纸

Carbon fiber paper fabricated by CVD for application of proton exchange membrane fuel cell

采用干法成型技术制备聚丙烯腈(PAN)基炭纤维纸坯体,用化学气相沉积(CVD)法将其制备成炭纸,并在2000℃进行石墨化处理。利用扫描电子显微镜(SEM)和偏光显微分析(PLM)观察炭纸及坯体的显微结构,利用X射线衍射仪测试炭纸的石墨化度,并利用四探针法测试炭纸的导电性能。研究结果表明:采用干法成型技术制备的炭纸坯体是由炭纤维随机堆积构成的网络结构,孔隙分布较均匀;采用CVD工艺所制备的热解炭具有粗糙层结构特征;炭纸中纤维由热解炭紧密连接;炭纸的平均石墨化度高达82.2%,大于日本Toray炭纸和加拿大Ballard炭纸的石墨化度。CVD法沉积的热解炭改善了炭纸的导电性能,其体电阻率为33.3m?.cm,低于Toray炭纸和Ballard炭纸的体电阻率(分别为45.2和135.9m?.cm);其面电阻率为6.0m?.cm,低于Toray炭纸和Ballard炭纸的面电阻率(分别为6.4和16.3m?.cm)。

PAN based carbon fiber paper （CFP） preform was fabricated using nonwoven fabrics method, and carbon fiber paper was obtained through chemical vapor deposition （CVD） technology and graphitization process at 2 000 ℃. The microstructures of CFP and its preform were observed by SEM and PLM, and the graphitization degree of CFP was determined by XRD. The electrical performances were measured using the four-probe technique. The results indicate that the as-prepared CFP preform by nonwoven fabrics method has a network structure with randomly accumulated carbon fibers and well-dispersed porosity. The results show that pyrocarbon through CVD process has rough laminar microstructure, and carbon fibers in the CFP are compactly connected by pyrocarbon. The average graphitization degree of CFP is up to 82.2% which is higher than those of Japan Toray CFP and Canada Ballard CFP. Pyrocarbon from CVD process improves electrical performance of CFP greatly, the through-plane electrical resistivity of the CFP is 33.3 mΩ·cm, while those of Toray and Ballard CFP are 45.2 and 135.9 mΩ·cm, respectively; the in-plane electrical resistivity of the CFP is 6.0 mΩ·cm, while those of Toray and Ballard CFP are 6.4 and 16.3 mΩ·cm, respectively.