Preparation of Polybenzimidazole/Lithium Hydrazinium Sulfate Composite Membranes for High‐Temperature Fuel Cell Applications

Abstract

PBI‐LiHzS composite membranes were prepared by casting N,N'‐DMAc solutions containing PBI and LiHzS, where the LiHzS contents in the membranes were between 2.5 and 10 wt.‐%. LiHzS was obtained by reacting hydrazine sulfate and lithium carbonate in water. PBI‐LiHzS composite membranes were thermally stable up to approximately 300 °C and their acid‐absorbing capabilities were comparable to those of the pure PBI membranes. The proton conductivity of PBI‐LiHzS composite membranes (2.12 × 10−2 S · cm−1 at 180 °C and 0% RH) was higher than that of pure PBI membranes when used at the same acid doping levels. The mechanical stability of the composite membranes having less than 5 wt.‐% of LiHzS was found to be close to that of pure PBI membranes.magnified image

Novel composite Zr/PBI-O-PhT membranes for HT-PEFC applications

“…Even carbon nanotubes were impregnated into PBI matrices for a higher durability [7–8]. In order to improve the conductivity, proton conductors such as heteropolyacids (H 3 SiW 12 O 40 (SiWA) [9–12], H 3 PW 12 O 40 (PWA) [12], Cs 2.5 H 0.5 PMo 12 O 40 (CsPMoA) [13]), lithium hydraziniumsulfate, LiN 2 H 5 SO 4 , (LiHzS) [14] and Zr-containing compounds (zirconium pyrophosphate [15], zirconium tricarboxybutylphosphonate [16–17]) were introduced into PBI membranes. According to the literature, researchers generally use quite high amounts (10–50%) of modifying agents when producing composite membranes.…”

Performance Investigation of Membrane Electrode Assemblies for High Temperature Proton Exchange Membrane Fuel Cell

“…Figure 1 shows the FT-IR spectra of the four ABPBI membranes. The characteristic peaks of PBI are shown in all membranes; hydrogen-bonded N-H stretching at 3184 cm −1 , the free non-hydrogen-bonded N-H stretching at 3415 cm −1 , and C=C and C=N stretching bands for benzimidazole group at 1612, 1590, and 1443 cm −1 can be observed from all the membrane samples [14], indicating that no significant structural changes took place in the bulk polymer of the above ABPBI membranes. However, it should be noted that sharp new peaks in the zone ranged between 800 and 1300 cm −1 are observed for the three modified ABPBI membranes (AM, AM 55 and AMcl), which are indicatives of interactions between the additives and ABPBI groups [11].…”

Advancement in Phosphoric Acid Doped Polybenzimidazole Membrane for High Temperature PEM Fuel Cells: A Review

“…Addition of HPAs was able to raise the proton conductivity by obstructing the water from escape out of the membrane at high temperature, reducing the dehydration of PA and also increase more acid site by providing extra help for proton transport. Another inorganic proton conducting solid, lithium hydrazinium sulfate (LiN2H5SO4, LiHzS) has been used in the nanocomposite PBI membrane [69]. Incorporation of LiHzS may have impact on proton conductivity, but it seems that the amount of LiHzS used must be kept at minimum level (<5%) as it has no outstanding enhancement on proton conductivity when more LiHzS was used.…”