Constructing stable continuous proton transport channels by in-situ preparation of covalent triazine-based frameworks in phosphoric acid-doped polybenzimidazole for high-temperature proton exchange membranes

Rational design of microporous polybenzimidazole framework for efficient proton exchange membrane fuel cells

“…The highest proton conductivity value of 0.24 S cm À1 was obtained with a 600 wt% (ADL 32) H 3 PO 4 loading, which is nearly 4 orders of magnitude higher than that of Ph-PyOPBI and removes the maximum proton conductivity barrier of all PBI systems under anhydrous conditions. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] We believe that the reasons for this high conductivity in the iptycene-based polymers are many fold, where rstly, there are stronger multiple hierarchical interactions (P]O/H-N, O-H/N]C and O-H/O-C) between the pyridine-functionalized oxypolybenzimidazole pore walls with the H 3 PO 4 networks, allowing the membranes to hold a large amount of PA, which can initiate the formation of continuous proton-conducting paths. 16,44 Secondly, the strong supramolecular edge-to-face p-p stacking interactions arising from the 3D iptycene units are helpful in preventing the membrane from swelling, while retaining the favourable PA uptake needed for maintaining high proton conductivity in the membrane.…”

“…3 Thus, in an attempt to address these issues, to date, much efforts has been focused on the development of various elegant strategies and synthetic approaches. [5][6][7][8][9][10][11][12][13][14] Unfortunately, no noticeably successful strategies have been reported thus far to resolve the abovementioned concerns and cause an improvement in the properties of PBI based HT-PEMs. As part of this viewpoint, in a recent effort, we strategically introduced a new type of alternative PBIs with soluble, readily accessible and processable pyridine-functionalized PBI (PyPBI) homo and copolymers as PEM candidates, which solved most of the concerns discussed above.…”

Constructing High-Density Hydrogen Bonding Networks via Introducing the Bipyridine Group for High-Performance Fuel Cell Proton Exchange Membranes

“…In the temperature range of 200–400 °C, a slight weight loss is observed in all TGA curves of the membranes due to the loss of residual solvents and small molecules . When the temperature further increases, the weight loss above 550 °C is due to the degradation of the benzimidazole backbone . In comparison with all the membranes, a dramatic weight loss at 200–400 °C is observed in the TGA curve of the cross-linking agent TGIC, which is attributed to the oxidative decomposition of its aliphatic group and the backbone …”

“…High-temperature proton exchange membrane fuel cells (HT-PEMFCs) have attracted a great deal of attention due to their simple hydrothermal management system, high platinum-based catalyst toxicity tolerance, and high output power density. − Phosphoric acid (PA)-doped polybenzimidazole (PBI) has exhibited the greatest potential as a high-temperature proton exchange membrane (HT-PEM), − since it can realize efficient proton transfer using PA as the proton carrier at high temperatures, and it also demonstrates good thermal stability, mechanical property, and chemical corrosion resistance. − It has been reported that the key to achieve high output power of the fuel cells is to improve the proton conductivity of the PBI membrane. , Doping large amounts of PA into the PEM is an efficient way to attain high conductivity. , However, the high concentration of PA will deteriorate the mechanical properties of the membrane due to the plasticization effect of the PA on the PEM. The PEM with low mechanical strength is not conducive to meeting the requirements of the cell assembly. ,, Therefore, it is challenge to achieve HT-PEMs with both high proton conductivity and high mechanical performance.…”

“…The PEM with low mechanical strength is not conducive to meeting the requirements of the cell assembly. 6,15,16 Therefore, it is challenge to achieve HT-PEMs with both high proton conductivity and high mechanical performance.…”