Antioxidant Sulfide-Linked Polymer Membrane with Inherent Microporosity Enables Fuel Cells to Achieve Outstanding Power Density and Durability Over a Wide Temperature Range

Abstract

Conventional phosphoric acid (PA) doped polybenzimidazole are regarded as the most promising materials for high-temperature proton exchange membrane fuel cells (HT-PEMFCs). Yet, their practical application has been hindered by their high production cost, poor oxidation stability, and loss of PA at low temperatures. Here, a polymer of intrinsic microporosity containing “sulfide-linkage” radical-sacrificial-agent is designed with good solubility and high PA retention, which enables it to operate for long periods at 80–180 °C. Specifically, the “sulfide-linkage” radical-sacrificial-agent enabled PSBI-IM to be durable for 100 h with mass retention still higher than 90%, and the capillary effect of the micropores enabled PSBI-IM/PA to retain more than 60% of PA under high humidity. After rational optimization, the cell assembled with PSBI-IM/PA achieved a power density of 1.62 W cm⁻² with a specific power of 2.7 W mg⁻¹ and an operating time of more than 500 h (0.2/0.4 A cm⁻²@160 °C). In addition, the voltage drop is only 5% even after 40 h of accelerated stress testing at 0.4 A cm⁻²@ 80 °C. Therefore, the PSBI-IM/PA can be stabilized over a wide temperature range from 80 to 160 °C, providing a new material for the HT-PEMFCs with flexible operational temperature.