Dataset for Non-fluorinated pre-irradiation-grafted (peroxidated) LDPE-based anion-exchange membranes with high performance and stability

Radiation-grafted anion-exchange membrane (RG-AEM) research has predominantly focused on the chemical stability of the polymer-bound positively-charged head-groups that enable anion conduction. The effect of the backbone polymer chemistry, of the precursor film, on RG-AEM stability has been studied to a lesser extent and not for RG-AEMs made from pre-irradiation grafting of polymer films in air. The mechanical strength of polymer films is generally weakened by exposure to high radiation doses and this is mediated by chemical degradation of the main chains: fluorinated films mechanically weaken at lower absorbed doses compared to nonfluorinated films. This study systematically compares the performance difference between RG-AEMs synthesised from a non-fluorinated polymer film (low-density polyethylene – LDPE) and a partially-fluorinated polymer film (poly(ethylene-cotetrafluoroethylene)– ETFE) using the peroxidation method. The RG-AEMs all contained identical covalently-bound benzyltrimethylammonium (BTMA) cationic head-groups. An LDPE-AEM achieved an OH– anion conductivity of 145 mS cm-1 at 80 °C in a 95% relative humidity environment. Alkali stability testing showed that the LDPE-AEM mechanically weakened to a much lower extent when treated in aqueous alkaline solution compared to the ETFE-AEM. This LDPE-AEM outperformed the ETFE-AEM in H2/O2 anion exchange membrane fuel cell tests due to high anion conductivity and enhanced in situ water transport: a maximum power density of 1.45 W cm-2 at 80 °C was achieved with an LDPE-AEM alongside a Pt-based anode and cathode (cf. 1.21 mW cm-2 for the ETFE-AEM). The development of more mechanically robust RG-AEMs has, for the first time, led to the ability to routinely test them in fuel cells at 80 °C. This development facilitates the application of non-Pt catalysts: 931 mW cm-2 was obtained with the use of a Ag/C cathode at 80 °C and a Ag loading of 0.8 mg cm-2. This first report on the synthesis of large batch size LDPE-based RGAEMs, using the commercially amenable peroxidation-type radiation-grafting process, concludes that the resulting LDPE-AEMs are superior to ETFE-AEMs (for the intended applications).