Impact of crosslinking in poly(naphthalene-co-terphenyl piperidinium) copolymer for anion exchange membrane fuel cells

Recent advancements in anion exchange membrane fuel cells (AEMFCs) have been driven by multiple factors, with significant contributions from developments in anion exchange membranes (AEMs). This study introduces long alkyl chains as crosslinkers within the poly(naphthalene-co-terphenyl piperidinium) (PBTP) framework to produce AEM, PBTP-c-x, with varying degrees of crosslinking. Comparative tests reveal that increased crosslinking in AEMs reduces both the water uptake and swelling ratio. The water uptake ratio and swelling ratio of PBTP-c-100 exhibits 21.3 % and 14 %, respectively. Its ionic conductivity is 94.38 mS·cm⁻¹ at 80 °C, compared to 113.04 mS·cm⁻¹ of PBTP-c-50. The increased crosslinking also strengthens the mechanical tensile properties of the membranes. PBTP-c-100 exhibiting a maximum mechanical tensile stress of 55.53 MPa, representing a 45 % improvement over PBTP. After 600-hours exposure to a 1 M NaOH solution at 60 °C, PBTP-c-100 shows negligible degradation, with a minimal hydroxide ionic conductivity loss of 5.31 %. Similarly, PBTP-c-50 experiences only a minor loss in conductivity, amounting to 5.82 %. PBTP-c-50 achieves a power density of 101.8 mW·cm⁻², compared to 96.7 mW·cm⁻² for pristine PBTP, indicating favorable single-cell performance for both membranes.