操作溫度在120℃~200℃的高溫質子交換膜燃料電池(High Temperature Proton exchange membrane fuel cell, HT-PEMFC)其優點包括:不需額外增濕系統、高CO容忍度並且可使用非白金觸媒等等的運用價值。目前以Nafion質子交換膜為主的PEMFC，其製造成本高昂，而造成市場推廣上的一大阻礙。近年來，摻雜磷酸的聚苯並咪唑(Polybenzimidazole,PBI)高分子由於其良好的耐熱性與質子傳導能力，常被研究作為HT-PEMFC之質子交換膜使用，以解決目前PEMFC所遇到的難題。而在本研究中，我們將以磷酸銻與PBI高分子混成複合膜材運用到HT-PEMFC中，並開發在未來可利用之價值。
金屬磷酸鹽類是以五氯化锑(Antimony Pentachloride)與磷酸(Phosphoric Acid)做為前驅物，在300℃與500℃下煅燒得到磷酸锑粉體，並測量質子傳導率與操作溫度之關係。煅燒300℃下的磷酸锑試片，質子傳導率隨磷銻莫爾比例的增加而提升，於30℃~260℃溫度範圍內，其質子傳導率皆高於1.010-2 S/cm。然而，在煅燒300℃下，摻雜各種陽離子之磷酸銻試片皆無助於提升原本材料的質子傳導率。而煅燒500℃之磷酸銻試片，其質子傳導率介於10-2 ~10-3 S/cm，明顯低於煅燒300℃之磷酸銻試片。因此，我們將煅燒300℃下，未摻雜陽離子之磷酸銻試片運用在HT-PEMFC上。另一方面，根據文獻上報導之方法，於聚磷酸(Poly-phosphoric acid, PPA)溶劑中合成出PBI高分子。而合成出的PBI經由固有黏度測定得知其分子量為4.9×104 g/mol。
磷酸銻/PBI之複合膜材，在未增濕氣氛下(PH2O~0.016atm)，操作溫度為160℃時具有最高質子傳導率為6.1×10-2 S/cm，明顯高於未混成的PBI膜材。而使用磷酸銻/PBI之複合膜材作為電解質膜並在觸媒層中加入白金觸媒與磷酸銻粉末作為質子導體，所構成的膜電極組最大電池功率密度可達121 mW/cm2。

High Temperature Proton exchange membrane fuel cells (HT-PEMFC), operated between 120C and 200C, promise to work without humidification, more tolerance to carbon monoxide poisoning, more flexibility in catalyst selection. These characteristics open up opportunities to cut down the price of PEMFC based on Nafion. And the HT-PEMFC based on the phosphoric acid doped PBI (Polybenzimidazole) has been developed recently and showed positive signs in achieving the above goals. In this investigation, we incorporate antimony phosphates into the HT-PEMFC based on PBI membrane and study its potential benefits.
We synthesize antimony phosphates using the precursors of antimony pentachloride and phosphoric acid, and calcine them at 300C and 500C. For the 300C calcined antimony phosphates, the proton conductivity increases with increasing molar ratio of phosphorus over antimony (P/Sb). In the P/Sb ratio between 3.0 and 4.0, the proton conductivities of 300C specimens are higher than 1.010-2 S cm-1 at 30 - 260C without humidification. While, the proton conductivities of 500C specimens are lower, 10-2 ~10-3 S cm-1 at 30 - 260C. A number of dopants have been added in the phosphate, but the proton conductivities are less than their corresponding values of the undoped specimens. Hence we incorporate the undoped antimony phosphate in HT-PEMFC, and these specimens are 300C calcined. On the other hand, the PBI powder has been synthesized in poly- phosphoric acid, according to the method reported in literature. And the molecular weight is estimated 4.9×104 g mol-1 using its viscosity data.
The composite membrane of PBI and antimony phosphate exhibits high proton conductivity, 6.1×10-2 S cm-1 at 160C. The proton conductivity of this composite membrane is higher than that of the phosphoric acid doped PBI membrane. With this electrolyte membrane and two electrodes loaded with the proton conductor of antimony phosphate and platinum catalyst, we fabricate a membrane-electrode assembly which produces electricity with the peak power value 121 mW cm-2.

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