Dimethylimidazolium-Functionalized Polybenzimidazole and Its Organic–Inorganic Hybrid Membranes for Anion Exchange Membrane Fuel Cells

Abstract

A quaternized polybenzimidazole (PBI) membrane was synthesized by grafting a dimethylimidazolium end-capped side chain onto PBI. The organic–inorganic hybrid membrane of the quaternized PBI was prepared via a silane-induced crosslinking process with triethoxysilylpropyl dimethylimidazolium chloride. The chemical structure and membrane morphology were characterized using NMR, FTIR, TGA, SEM, EDX, AFM, SAXS, and XPS techniques. Compared with the pristine membrane of dimethylimidazolium-functionalized PBI, its hybrid membrane exhibited a lower swelling ratio, higher mechanical strength, and better oxidative stability. However, the morphology of hydrophilic/hydrophobic phase separation, which facilitates the ion transport along hydrophilic channels, only successfully developed in the pristine membrane. As a result, the hydroxide conductivity of the pristine membrane (5.02 × 10−2 S cm−1 at 80 °C) was measured higher than that of the hybrid membrane (2.22 × 10−2 S cm−1 at 80 °C). The hydroxide conductivity and tensile results suggested that both membranes had good alkaline stability in 2M KOH solution at 80 °C. Furthermore, the maximum power densities of the pristine and hybrid membranes of dimethylimidazolium-functionalized PBI reached 241 mW cm−2 and 152 mW cm−2 at 60 °C, respectively. The fuel cell performance result demonstrates that these two membranes are promising as AEMs for fuel cell applications.

Quarternized polysulfone/ZSM‐5 zeolite composite anion exchange membrane separators for aluminum‐air battery

“…This is a similar trend as observed for the % content of WU in Table1. A similar behavior with increasing hydration number with increasing WU and decreasing IEC has been reported in the literature 50,51. This indicates that the composite membrane fabricated in this work favors hydroxide transportation via vehicular movement which is possible when the membrane is hydrated.…”

“…A similar behavior with increasing hydration number with increasing WU and decreasing IEC has been reported in the literature. 50,51 This indicates that the composite membrane fabricated in this work favors hydroxide transportation via vehicular movement which is possible when the membrane is hydrated. IC measures ion transport from one electrode to another in an Al-air battery.…”

Anion Exchange Membranes Based on Imidazoline Quaternized Polystyrene Copolymers for Fuel Cell Applications

“…We supposed that the more water content may allow the molecules to diffuse more efficiently in a membrane. Accordingly, the ion transport in the PSVBIm-30 and PSVBImn-50 membranes prefer via vehicular mechanism (Ea < 14 KJ/mol) instead of Grotthuss mechanism [34].…”

“…We supposed that the more water content may allow the molecules to diffuse more efficiently in a membrane. Accordingly, the ion transport in the PSVBIm-30 and PSVBImn-50 membranes prefer via vehicular mechanism (Ea < 14 KJ/mol) instead of Grotthuss mechanism [34]. As summarized in Table 3, the hydroxide conductivity measured at 30 °C of the PSVBImn-50 membrane containing imidazolinium cations was comparable to some of those AEMs based on poly(St-co-VBC) containing quaternary ammonium or imidazolium cations, such as QMSV-0.33, Poly(St-co-VBMI), and Membrane-1 (TMA), reported in the literature [2,7,27,35].…”

Hydrogen bond-dominated polybenzimidazole semi-interpenetrating network membranes for alkaline water electrolysis

“…On the one hand, quaternary ammonium or sulfonate functionalization of PBI has been considered as a feasible approach. [22][23][24][25] Jheng et al 23 synthesized quaternary ammonium PBI membranes by graing a dimethylimidazole end-capped side chain onto PBI, and then prepared organic-inorganic hybrid membranes of quaternary ammonium PBI by a silane-induced crosslinking process with triethoxysilylpropyl dimethylimidazole chloride, resulting in good hydroxide conductivity and alkali resistance stability. Hu et al 25 designed sulfonate-graed poly(2,2 ′ -(1,4-naphthalene)-5,5 ′ -benzimidazole) (NPBI); using the reactive N-H group of NPBI, hydrophilic sulfonate side chains were attached to the PBI backbone by ring-opening reactions, thereby inducing the formation of hydrophilic regions and improving the electrolyte (KOH) uptake, leading to a higher hydroxide ionic conductivity.…”