A general strategy to enhance the alkaline stability of anion exchange membranes

Abstract

Carbonyl groups protect quaternary ammonium groups by reversible reaction with OH− ions. This protection is named the “rat-trap effect”.

Enhanced Hydroxide Conductivity and Dimensional Stability with Blended Membranes Containing Hyperbranched PAES/Linear PPO as Anion Exchange Membranes

“…The alkaline stability of AEMs is a critical parameter, AEMs must operate in high pH environments in FC applications [ 59 , 60 , 61 , 62 ]. In general, the quaternary ammonium groups of the AEMs disintegrate in a harsh alkaline condition as the result of the OH − attack via Hofmann elimination and direct nucleophilic substitution [ 47 , 63 ].…”

Properties and Alkaline Stability of Composite Anion Conducting Ionomers Based on Poly(phenylene oxide) Grafted with DABCO and Mg/Al Lamellar Double Hydroxide

“…However, the availability of such membranes would allow avoiding the extensive use of platinum or related expensive noble-metal electrocatalysts for the oxygen reduction reaction [9][10][11]. The alkaline degradation can occur on functional groups, especially quaternary ammonium moieties [12][13][14][15], but also on the polymer backbone [3,16], especially if it contains electron-withdrawing groups, such as sulfone. Polysulfones (PSU) [17,18] are therefore considered less alkaline stable polymers and ionomers based on poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), which do not contain sulfone links, are expected to present a higher alkaline stability [15,[19][20][21][22][23][24], although the ether groups are still possible weak points [25][26][27].…”

Comb-shaped cardo poly(arylene ether nitrile sulfone) anion exchange membranes: significant impact of nitrile group content on morphology and properties

“…As a clean and highly efficient renewable energy conversion device, the fuel cell has attracted considerable attention in the last decade. [1][2][3] Of various fuel cell types, alkaline electrolyte membrane fuel cells (AEMFCs) hold particular attention with their merits of faster oxygen reduction reaction kinetics 4 and their potential to use non-precious metal catalysts (e.g., metal oxides 5 and transition metals 6,7 ), which could signicantly reduce the cost of production. As a key component of AEMFCs, anion exchange membranes (AEMs) have an important effect on the whole electrochemical performance of fuel cells.…”