Anion exchange membranes derived from nafion precursor for the alkaline fuel cell: Effect of cation type on properties

Abstract

Highly stable hydroxide conducting membranes are necessary for solid-state alkaline fuel cells to have long performance lifetimes. In this study, we used solid-state chemistry to synthesize Nafion-based anion exchange membranes (AEMs) with a variety of covalently attached cations, including trimethylammonium, trimethylphosphonium, piperazinium, pyrrolidinium, pyridinium, and quaternized 1,4-diazabicyclo[2.2.2]octane. Infrared spectroscopy confirms a partial asymmetric functionalization of all cations with the exception of pyridinium. The AEMs that were successfully synthesized all exhibited sufficient water uptake and conductivity. The effect of cation type on AEM chemical and thermal stability was investigated as a function of various conditions (e.g., hydration levels, temperature, and pH). High chemical and thermal stability was observed for all successfully synthesized AEMs with the exception of the trimethylphosphonium cation AEM.

Synthesis of perfluorinated ionomers and their anion exchange membranes

“…Recently, several studies have report on the perfluorinated AEMs from Nafion s or 3 M perfluorosulfonyl fluoride (PFSO 2 F) precursor via amination of the PFSO 2 F precursor with variety of covalently attached cations including trimethylammonium (TMA), 1, 4 -dimethylpiperazine (DMP), quaternized 1, 4-diazabicyclo [2.2.2] octane(DABCO) and guanidinium, and so on [22][23][24][25][26]28]. The F À form AEMs can be generated by the reaction of the 3 M or Nafion s precursor performed under rigorously anhydrous conditions.…”

The impact of alkyl tri‐methyl ammonium side chains on perfluorinated ionic membranes for electrochemical applications

“…Bosnjakovic et al also synthesized a polymer from 3M precursor, where they have identified the SO 2 stretching peak at 1467 cm −1 . Salerno et al used a modified Nafion® AEM . They have reported that the CF 2 stretch is observed around 1200 cm −1 .…”

“…Salerno et al used a modified Nafion ® AEM. 18 They have reported that the CF 2 stretch is observed around 1200 cm −1 . In addition to the literature related to perfluorinated AEM, we have referred to FTIR literature of Nafion ® as the polymers studied in this research are very similar to Nafion ® .…”

“…It was further investigated by Varcoe et al that the synthesis approach followed by Jung and Salerno et al yielded polymer unsuitable for anion exchange applications. 17,18,21 The two AEMs (PFAEM_CH3_C3 and PFAEM_CH3_C6) discussed in this article follow a synthesis procedure reported previously by Park et al 22 These AEMs were synthesized using 3M ionomer (EW 800) as a precursor, which has a shorter side chain than Nafion ® that theoretically could yield higher ionic conductivity and/or improved mechanical properties. 22 The two AEMs studied had methylated sulfonamide linkages to the 3M backbone with either three or six methylene groups serving as a tether to a tri-methyl ammonium cation as shown in Figure 1.…”

Strategies for Developing New Anion Exchange Membranes and Electrode Ionomers

“…See 13.66.222.141 Downloaded on 2019-04-08 to IP perfluorinated polymers and the carboxylate form of Nafion. [44][45][46] These membranes derived from commercially available precursors, still require further optimization for robust alkaline stability at elevated temperatures and for use in electrochemical devices with high current density operation.…”