Hydrophilic–Hydrophobic Bulky Units Modified Anion Exchange Membranes for Fuel Cell Application

The hydroxide conductivity and alkaline stability play a significant role in the application of an anion exchange membranes (AEMs) fuel cell. These high performances are closely related to the structure of the polymer. Side-chain structure is commonly used to construct microphase separation. On this basis, a new strategy is to incorporate a rigid bulky structure into an AEM to break chain packing and reduce resistance against hydroxide ion transport. In this work, rigid bulky hydrophilic–hydrophobic side-chain grafted, ether-free poly(biphenyl indole) (PBN) AEMs are designed and prepared by chemical incorporation of hydrophilic bulky cyclodextrin and hydrophobic bulky adamantane onto the PBN backbone. The enhanced driving force of microphase separation and the enlarged free volume can make for high hydroxide conductivity. The fabricated AEM with an ion exchange capacity (IEC) of 1.81 mmol g–1 shows a conductivity of 122.0 mS cm–1 at 80 °C, which can be retained by 90% after treatment of the AEM in a 1 M NaOH solution at 80 °C for 1008 h. Its single H2/O2 fuel cell yields a peak power density of 603 mW cm–2 at 60 °C; the fuel cell can maintain 70.2% of its initial voltage after operating for 30 h. This strategy provides a new and effective route for the preparation of AEMs with superior performance.