Poly(Ethylene Piperidinium)s for Anion Exchange Membranes

Abstract

The lack of anion exchange membranes (AEMs) that possess both high hydroxide conductivity and stable mechanical and chemical properties poses a major challenge to the development of high‐performance fuel cells. Improving one side of the balance between conductivity and stability usually means sacrificing the other. Herein, we used facile, high‐yield chemical reactions to design and synthesize a piperidinium polymer with a polyethylene backbone for AEM fuel cell applications. To improve the performance, we introduced ionic crosslinking into high‐cationic‐ratio AEMs to suppress high water uptake and swelling while further improving the hydroxide conductivity. Remarkably, PEP80‐20PS achieved a hydroxide conductivity of 354.3 mS cm−1 at 80 °C while remaining mechanically stable. Compared with the base polymer PEP80, the water uptake of PEP80‐20PS decreased by 69 % from 813 % to 350 %, and the swelling decreased substantially by 85 % from 350.0 % to 50.2 % at 80 °C. PEP80‐20PS also showed excellent alkaline stability, 84.7 % remained after 35 days of treatment with an aqueous KOH solution. The chemical design in this study represents a significant advancement toward the development of simultaneously highly stable and conductive AEMs for fuel cell applications.

Microcrystalline-Induced Physical-Cross-linking toward a High Performance Hyper-Branched Anion Exchange Membrane

“…7 Encouragingly, some significant progress has been achieved in terms of chemical stability and ionic conductivity of AEMs. 8,9 For example, AEMs based on the poly(norbornene) block copolymer showed <1.35% degradation after aging in 1 M NaOH at 80 °C for 1000 h; the OH − conductivity was as high as 201 mS cm −1 at 80 °C with a peak power density of 3.21 W cm −2 . 10 Particularly, the AEMs based on poly(aryl piperidine) (PAP) derivatives has shown both excellent alkaline stability (≥5000 h) and high ion conductivity (208 mS cm −1 @80 °C), as well as satisfied fuel cell performance (2.58 W cm −2 @80 °C at H 2 −O 2 ), in recent years.…”

“…The anion exchange membrane fuel cell (AEMFC) is an important technology for achieving renewable energy conversion and is receiving increasing attention for their potential commercial value. , Mainly due to the fast oxygen reduction reaction (ORR) kinetic, AEMFC allows for the use of nonprecious metals as catalysts, which significantly reduces the cost of the fuel cell. − However, there are many challenges regarding the anion exchange membranes (AEMs), which is a key component of the AEMFC, such as low chemical and mechanical stability and insufficient ion conductivity . Encouragingly, some significant progress has been achieved in terms of chemical stability and ionic conductivity of AEMs. , For example, AEMs based on the poly­(norbornene) block copolymer showed <1.35% degradation after aging in 1 M NaOH at 80 °C for 1000 h; the OH – conductivity was as high as 201 mS cm –1 at 80 °C with a peak power density of 3.21 W cm –2 . Particularly, the AEMs based on poly­(aryl piperidine) (PAP) derivatives has shown both excellent alkaline stability (≥5000 h) and high ion conductivity (208 mS cm –1 @80 °C), as well as satisfied fuel cell performance (2.58 W cm –2 @80 °C at H 2 –O 2 ), in recent years. − …”

Four-arm star-shaped high-performance poly(aryl piperidine) anion exchange membranes for fuel cells

“…4–6 Nevertheless, PEMFC advancement has not been devoid of challenges, particularly owing to the pervasive reliance on expensive platinum group metals (PGMs) as the eletrocatalysts. 5,7–10 In this context, anion exchange membrane fuel cells (AEMFCs) have attracted considerable attention as a promising alternative to their PEMFC counterparts. The rationale behind this burgeoning interest is rooted in the superior oxygen reduction kinetics and the cost-effectiveness of catalysts attributed to the high-pH working conditions within AEMFCs, which collectively position them as viable substitutes for PEMFCs.…”

“…9,23 Previous studies have shown that using aryl-ether free polymers and piperidinium-type cationic groups can effectively improve the performance of AEMs. 8,24 Bae et al demonstrated the synthesis of high molecular weight poly(biphenyl olefin) membranes with exceptional resistance to alkaline conditions. 25 Hu et al prepared poly(aryl piperidine) membranes, which showed no degradation even after prolonged immersion in 1 M KOH for 2000 hours.…”

Ultramicroporous Tröger’s Base Framework Membranes for pH-Neutral Aqueous Organic Redox Flow Batteries

“…Ion exchange membranes (IEMs) are key materials to an array of energy and environment-related technologies, such as H 2 /O 2 fuel cells, − aqueous organic redox flow batteries (AORFBs), − water electrolysis, − osmotic energy-conversion devices, , ion-capture electrodialysis, etc. In these technologies, IEMs selectively transport specific ions and simultaneously act as electrical insulators.…”