Branched polybenzimidazole / polymeric ionic liquid cross-linked membranes with high proton conductivity and mechanical properties for HT-PEM applications. (15th February 2023)

• Record Type: Journal Article
• Authors: Sun, Han; Wang, Shuang; Cui, Yinghe; Yong, Zhipeng; Liang, Dan; Wang, Xiaodong; Wang, Xiaorui; Li, Chenglong; Pan, Feng; Wang, Zhe
• Is Part Of: International journal of hydrogen energy. Volume 48:Number 14(2023)
• Page Start: 5618
• Page End: 5629
• Publication Date: 2023-02-15
• Subjects: Proton exchange membranes -- Branched structure -- Large free volume -- Cross-linkable polymeric ionic liquid -- High proton conductivity; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2022.07.222
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Branched polymers have unique three-dimensional dendritic structures, so they have received a lot of attention in the application of high temperature proton exchange membranes. In this work, we synthesize BOPBI-X (X = 3%, 6%, 9%) membranes with different branched ratios based on the synthesis of OPBI, due to the introduction of a rigid triazine structure with a larger free volume, the membranes could absorb more phosphoric acid (PA) while maintaining sufficient mechanical strength. Among them, the BOPBI-6% membrane obtains splendid comprehensive performance, when the PA doping level (ADL) is 9.55, it achieves a proton conductivity of 99.2 mS cm −1 at 180 °C, which is 1.8 times higher than OPBI (54.8 mS cm −1 ), and it performs well in long-term oxidation stability test after 144 h, it still has a mass retention rate of 90%. For the sake of further boost the performance of the membrane, cross-linkable polymeric ionic liquid (PIL) is introduced to the system. Among them, BOPBI-PIL-30% membrane has sufficient mechanical properties (5.50 ± 0.8 MPa), and the proton conductivity (146.9 mS cm −1 ) at 180 °C is also excellent, so BOPBI-PIL-30% membrane is expected to be a promising candidate as HT-PEMs. Highlights: The branched membrane has excellent PA doping level and proton conductivity. The BOPBI-6% membrane has excellent oxidative stability. PIL can improve proton conductivity while improving mechanical properties.