Phosphoric acid-doped polybenzimidazole with a leaf-like three-layer porous structure as a high-temperature proton exchange membrane for fuel cells

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2021-11, Vol.9 (46), p.26345-26353
• Main Authors: Wang, Peng, Peng, Jinwu, Yin, Bibo, Fu, Xianzhu, Wang, Lei, Luo, Jing-Li, Peng, Xiaojun
• Format: Article
• Language: English
• Subjects: Crosslinking; Durability; Fuel cells; Fuel technology; High temperature; Leaves; Mechanical properties; Membranes; Phosphoric acid; Polybenzimidazoles; Proton exchange membrane fuel cells; Protons
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d1ta06883k

Porous polybenzimidazole (PBI) membranes with a high ability to store phosphoric acid (PA) and transfer protons are promising materials as high-temperature proton exchange membranes (HT-PEMs) for fuel cell applications. However, porous PA-doped PBI membranes show poor mechanical properties due to porous structure and the PA plasticizing effect. Herein, a new leaf-like three-layer porous PA-doped PBI HT-PEM is designed and prepared, which contains an inside porous layer and two dense skin layers as the protected layers. Such a unique structure endows PA-doped PBI to reach a high PA-doping level, thus improving the proton exchange performance. The as-prepared three-layer HT-PEM exhibits the highest peak power density of 713 mW cm −2 , superior to that of a two-layer membrane (551.1 mW cm −2 ). Additionally, the durability of three-layer HT-PEM fuel cells is greatly enhanced through a cross-linking method, and only 0.064 mV h −1 decay of load voltage is observed after 200 h. These results indicate that the introduction of a leaf-like three-layer porous structure is an effective strategy to design HT-PEMs with excellent performance for fuel cell applications. Leaf-like three-layer porous PBI HT-PEMs with excellent power density and durability, which break through the limits of porous membranes.