Young Jun Lee

Alkaline polymer electrolytes (APEs) are essential materials for alkaline energy conversion devices such as anion exchange membrane fuel cells (AEMFCs) and water electrolyzers (AEMWEs). Here, we report a series of branched poly(aryl‐co‐aryl piperidinium) with different branching agents (triptycene: highly‐rigid, three‐dimensional structure; triphenylbenzene: planar, two‐dimensional structure) for high‐performance APEs. Among them, triptycene branched APEs showed excellent hydroxide conductivity (193.5 mS cm⁻¹@80 °C), alkaline stability, mechanical properties, and dimensional stability due to the formation of branched network structures, and increased free volume. AEMFCs based on triptycene‐branched APEs reached promising peak power densities of 2.503 and 1.705 W cm⁻² at 75/100 % and 30/30 % (anode/cathode) relative humidity, respectively. In addition, the fuel cells can run stably at a current density of 0.6 A cm⁻² for 500 h with a low voltage decay rate of 46 μV h⁻¹. Importantly, the related AEMWE achieved unprecedented current densities of 16 A cm⁻² and 14.17 A cm⁻² (@2 V, 80 °C, 1 M NaOH) using precious and non‐precious metal catalysts, respectively. Moreover, the AEMWE can be stably operated under 1.5 A cm⁻² at 60 °C for 2000 h. The excellent results suggest that the triptycene‐branched APEs are promising candidates for future AEMFC and AEMWE applications.

Alkaline polymer electrolytes (APEs) are essential materials for alkaline energy conversion devices such as anion exchange membrane fuel cells (AEMFCs) and water electrolyzers (AEMWEs). Here, we report a series of branched poly(aryl‐co‐aryl piperidinium) with different branching agents (triptycene: highly‐rigid, three‐dimensional structure; triphenylbenzene: planar, two‐dimensional structure) for high‐performance APEs. Among them, triptycene branched APEs showed excellent hydroxide conductivity (193.5 mS cm⁻¹@80 °C), alkaline stability, mechanical properties, and dimensional stability due to the formation of branched network structures, and increased free volume. AEMFCs based on triptycene‐branched APEs reached promising peak power densities of 2.503 and 1.705 W cm⁻² at 75/100 % and 30/30 % (anode/cathode) relative humidity, respectively. In addition, the fuel cells can run stably at a current density of 0.6 A cm⁻² for 500 h with a low voltage decay rate of 46 μV h⁻¹. Importantly, the related AEMWE achieved unprecedented current densities of 16 A cm⁻² and 14.17 A cm⁻² (@2 V, 80 °C, 1 M NaOH) using precious and non‐precious metal catalysts, respectively. Moreover, the AEMWE can be stably operated under 1.5 A cm⁻² at 60 °C for 2000 h. The excellent results suggest that the triptycene‐branched APEs are promising candidates for future AEMFC and AEMWE applications.

The rational design of the current anion exchange polyelectrolytes (AEPs) is challenging to meet the requirements of both high performance and durability in anion exchange membrane water electrolyzers (AEMWEs). Herein, highly‐rigid‐twisted spirobisindane monomer is incorporated in poly(aryl‐co‐aryl piperidinium) backbone to construct continuous ionic channels and to maintain dimensional stability as promising materials for AEPs. The morphologies, physical, and electrochemical properties of the AEPs are investigated based on experimental data and molecular dynamics simulations. The present AEPs possess high free volumes, excellent dimensional stability, hydroxide conductivity (208.1 mS cm⁻¹ at 80 °C), and mechanical properties. The AEMWE of the present AEPs achieves a new current density record of 13.39 and 10.7 A cm⁻² at 80 °C by applying IrO₂ and nonprecious anode catalyst, respectively, along with outstanding in situ durability under 1 A cm⁻² for 1000 h with a low voltage decay rate of 53 µV h⁻¹. Moreover, the AEPs can be applied in fuel cells and reach a power density of 2.02 W cm⁻² at 80 °C under fully humidified conditions, and 1.65 W cm⁻² at 100 °C, 30% relative humidity. This study provides insights into the design of high‐performance AEPs for energy conversion devices.