China
Africa
Explore chapters and articles related to this topic
Applications of Carbon Materials in Membranes for Fuel Cells
Published in Shuhui Sun, Xueliang Sun, Zhongwei Chen, Yuyu Liu, David P. Wilkinson, Jiujun Zhang, Carbon Nanomaterials for Electrochemical Energy Technologies, 2017
Polybenzimidazole (PBI) refers to amorphous thermoplastic polymers with linear heterocyclic polymers containing a benzimidazole nucleus as a repeat unit. It has high thermal stability (glass transition temperature, Tg = 425°C–436°C), excellent chemical resistance, retention of stiffness and toughness, and good membrane-forming properties [8,9]. PBI with PA is an ideal electrolyte for use in PEMFCs between 100°C and 200°C, but the low conductivity and PA flooding in membrane are still problems. So, GO is used as a modifier in the PBI/PA membrane to enhance the conductivity and reduce the PA doping level. PBI-based fuel cells exhibit significant activation polarization, with overpotential of some 0.25 V at 0.1 A cm−2, and GO/PBI- and Sulphonated Graphite Oxide (SGO)/PBI-based fuel cells exhibit similar overpotentials of around 0.2 V at 0.1 A cm−2. The performance of the cells with the GO/PBI and SGO/PBI composite membranes is significantly better than with the PBI membrane shown in Figure 11.3. The peak power densities of PBI, GO/PBI, and SGO/PBI with oxygen are 0.22, 0.38, and 0.6 W cm−2, respectively. The better performance is mainly attributed to superior proton conductivity and also the strong acid and water retention properties of the composite membrane at low acid loading. Hydrogen bonds in GO, which form acidic functional groups such as carboxylic acid and epoxy oxygen, could provide more facile hopping of protons to enhance the conductivity, and the SO3H− group in SGO also benefits conductivity. Also, SGO/PBI with low PA loading level provides good performance, which is even higher than that of greater (11.0 M) PA-loaded PBI membrane. Functional GO will help to reduce the H3PO4 doping level for PBI membranes [34].
Solid Polymer Electrolyte Membranes
Published in Asit Baran Samui, Smart Polymers, 2022
Swati S. Rao, Manoranjan Patri
As discussed in the preceding sections, membranes derived from hydrocarbon-based polymers have been found to be suitable for fuel cell operation as an alternative to Nafion®. However, most of these membranes still depend on humid operational conditions to be useful under real fuel cell conditions. This limits their usage to temperatures of 120°C. First, when a polymer electrolyte fuel cell is operated at temperatures below 120°C, the requirement of pure hydrogen gas becomes stringent. Hydrogen gas with a minimum 99.999% purity is required, otherwise slight traces of carbon monoxide will poison the platinum catalyst and lead to a drop in performance. Second, water management is a major concern. Thus, more complexity is added to the system as a whole in terms of commercialization. When the fuel cell is operated at 150°C and above, the tolerance of the catalyst to carbon monoxide increases to 10,000 ppm. Polybenzimidazole (PBI) membranes have been found to be the most suitable for application in fuel cells operating at a higher temperature (Mader et al. 2008). These membranes offer the advantage of high thermal (Samms et al. 1996) and mechanical stability (Appleby 1996; He et al. 2006) and high conductivity (He et al. 2003; Ma et al. 2004) under dry conditions. PBI Performance Innovations Inc. is the main global manufacturer of PBI products, including powder, solution (with DMAc as the solvent), and PBI fibers in various forms. Those prominent among different types of PBI polymers are poly [2,2’-(meta-phenylene),5,5’-(bibenzimidazole)] (PBI) (Li et al. 2004) and poly(2,5-benzimidazole) (ABPBI) (Asensio and Gomez-Romero 2005) (Figure 14.14). ABPBI polymer has a simpler structure compared to PBI. It is synthesized from a single monomer and hence is less expensive. Also, since it has a higher number of basic sites, it tends to absorb more acid compared to PBI at the same acid bath concentration.
Industrial Polymers
Published in Manas Chanda, Plastics Technology Handbook, 2017
Polybenzimidazole (PBI) is the most well-known commercial example of aromatic heterocycles used as high-temperature polymers. The synthesis of PBI is carried out as follows (see also Figure 1.36). The tetraaminobiphenyl required for the synthesis of PBI is obtained from 3,3′-dichloro-4,4′-diaminodiphenyl (a dye intermediate) and ammonia. Many other tetraamines and dicarboxylic acids have been condensed to PBI polymeric systems.
Numerical study of vapor behavior in high temperature PEM fuel cell under key material and operating parameters
Published in International Journal of Green Energy, 2022
Xia Lingchao, Zhang Caizhi, Jinrui Chen, Liang Chen, Meng Ni, Deng Bo, Xu Jiangfeng
Membrane materials and H3PO4 doping level of the membrane are two of the key parameters that may affect cell performance (Chen et al. 2019). Nowadays, polybenzimidazole (PBI) membrane is the most commonly used material for HT-PEMFC among all kinds of membrane materials, such as Nafion (Chen et al. 2017), polybenzimidazole/polytetrafluoroethylene (PBI/PTFE) membrane (Lin, Yu et al. 2007), and perfluorosulfonic acid membrane (Endoh 2008). Chen et al. (Chen and Lai 2010) reported that the conductivity of a PBI membrane is less dependent on the vapor than a Nafion membrane. Lin et al. (Lin, Yu et al. 2007) reported that the PBI/PTFE-2 membrane would have higher proton conductivity than that of Nafion membrane, while its value is less than that of PBI membrane. Different membranes also have different porous structures inside. Thus, the vapor behavior of fuel cell with different membrane materials would be different. For the doping level of H3PO4, Li et al. (Li et al. 2004) experimentally found that the PBI membranes’ vapor uptake from high acid concentrations solution is associated with the H3PO4 doping level, but no further investigations were conducted in vapor environment. Scholta et al. (Scholta et al. 2009) reported that the uneven vapor transport in a stack may cause the inhomogeneity voltage of each single cell that leads to the reduction of the stack’s life (Scholta et al. 2008). Thus, the types of membrane material and membrane H3PO4 doping level may affect vapor behavior in HT-PEMFC.
Reaction of ozone with polybenzimidazole (PBI)
Published in Ozone: Science & Engineering, 2018
Omran Omar, Bao Ha, Katerine Vega, Andrew Fleischer, Hyukin Moon, Joel Shertok, Alla Bailey, Michael Mehan, Surendra K. Gupta, Gerald A. Takacs
Poly[2,2ʹ-m-(phenylene)-5,5ʹ-bibenzimidazole], better known as polybenzimidazole (PBI), or meta-PBI, is a high-performance polymer consisting of benzimidazole units, as shown in Figure 1, having high thermal stability, chemical resistivity, and mechanical strength making it suitable for many applications (Li et al. 2009). PBI fibers are used in the fabrication of firefighters’ suits (Davis et al. 2010; Wainright et al. 1995), aerospace space suits (Bhatnagar et al. 2011), as well as, in high temperature proton exchange membrane fuel cells (HT-PEMFCs) where PBI film is doped with phosphoric acid (H3PO4) (Kondratenko, Gallyamov, and Khokhlov 2012; Li et al. 2009; Quartarone and Mustarelli 2012; Wainright et al. 1995). The proton conductivity is a result of proton transfer via hydrogen bonding between phosphoric acid and the nitrogen-containing groups in PBI.