Fuel cell performance improvement via the steric effect of a hydrocarbon-based binder for cathode in proton exchange membrane fuel cells

Abstract

In this study, a sulfonated poly(ether sulfone) having cardo-type fluorenyl groups (FL-SPES) was investigated as a cathodic binder to improve fuel cell performance via increased the oxygen diffusion in the cathode. The maximum power density achieved by using the membrane electrode assembly (MEA) prepared with FL-SPES with a low ion exchange capacity (IEC) of 1.31 meq g–1 was 520 mW cm–2, which is more than twice as high as that of BP-SPES (210 mW cm–2) having typical biphenyl groups with a similar IEC. At high IEC of 1.55 meq g–1, the power density obtained by using BP-SPES was improved to 454 mW cm–2 but remained lower than that of FL-SPES. In addition, although the IEC, swelling degree, and specific resistance were similar to each other, the gas permeability of FL-SPES was improved by approximately three times compared to that of BP-SPES. The steric structure of cardo-type FL-SPES increased the free volume between the polymer backbones, leading to an increase in gas transfer. Consequently, oxygen diffusion was promoted at the cathode, resulting in improved fuel cell performance.

Proton exchange membrane fuel cells: application for value-added chemical productions

“…Compared to low-temperature membranes, developing membrane materials that can be used at higher temperatures can enhance the system's tolerance to pollutants, reduce the use of precious metal catalysts, and simplify the system by eliminating the need for liquid water operation. The types of high-temperature membranes currently developed and their proton conductivities are shown in Table 3 [38] . Currently, the PEMs used in the production of chemicals using PEMFCs and in chemical production and chemicals and electricity co-generation systems are mostly commercial Nafion membranes; research on the involved membrane materials and their modification are relatively lacking.…”

“…In addition to the amount, the type and properties of ionomer binders can also affect the performance of PEMFCs in electricity generation [39,40] , but no related reports have been found in the production of chemicals and the co-generation of chemicals and electricity using PEMFCs. This table is quoted with permission from Meyer et al [38] published in Electrochem Energy Rev. A-MCM-41: Anhydrous m-PBI composite membrane using Al-substituted mesoporous silica; HT-PEMs: high-temperature polymer electrolyte membranes; NPs: nanoparticles; PBI: polybenzimidazole; PBI-OO: polybenzimidazole; PA: phosphoric acid; PES: poly(ethersulfone); PTFE: polytetrafluoroethylene; PVP: poly(vinyl pyrrolidone).…”

Binder design strategies for cathode materials in advanced secondary batteries

“…Nonetheless, its cost and inadequate thermal stability have prompted the search for more cost-effective and thermally stable alternatives. 241,242…”

“…246 A sulfonated poly(ether sulfone) containing cardo-type fluorenyl groups was used as the cathode binder. 242 Compared with the sulfonated poly-(ether sulfone)-containing biphenyl groups, its stereoscopic structure increased the free volume of the polymer skeleton, which could accelerate the oxygen diffusion rate and reduce the polarization.…”