Microphase separation structures facilitated by dipole molecules and hydrogen bonding in poly (biphenyl piperidine-isatin) anion exchange membranes

Abstract

The anion exchange membranes (AEMs) have the important function of blocking fuel and conducting OH− to make the cell form a circuit, so its alkali stability directly affects the performance of alkaline fuel cells. Currently, AEMs face a “trade-off” between ionic conductivity and stability. In order to solve this problem, we optimize the alkali resistance and conductivity of AEMs by introducing dipole-interacting side chains and hydrophilic hydroxyl side chains acting simultaneously on a rigid polymer backbone. By adopting the design strategy of “1 + 1>2″, the ion channel efficiency also makes a high-speed leap from a “two-wheeled bicycle” to a “four-wheeled car”. This effective microscopic modulation is clearly demonstrated by transmission electron microscope (TEM), where the AEMs after molecular design carry out a more obvious microphase separation structure at 200 nm. Through the PBP-54-IS- [OPD-100-OH-0] membrane, the maximum ionic conductivity is 100.62 mS cm−1 at 80 °C. After 1000 h at 80 °C, the retention rate of OH− conductivity of all AEMs was over 88.24 %. We also test its fuel cell performance for analysis. When the temperature of the two poles is 75 °C/72 °C, the power density is 147.28 mW cm−2. These are in line with the inherent requirements of AEMs for fuel cell applications.