Progress and challenges on air-cooled open-cathode proton exchange membrane fuel cells: Materials, structures, and systems

Air-cooled open-cathode proton exchange membrane fuel cells (AO-PEMFCs), with a greatly simplified balance-of-plant concept and compact structure, exhibit advantages of significantly reduced weight, low energy consumption, low operating temperature and low parasitic power. As a new star in research field of fuel cell, AO-PEMFCs shows great superiority for small-size portable power source, especially unmanned aerial vehicles, backup generators, and off-grid or emergency power applications. In this paper, we outlined recent improvements and advances in AO-PEMFCs, and discussed the fundamental research and technology status, including material developments, structure design, system and stack optimization, as well as their applications. This review aims to comprehensively discuss the research progress of AO-PEMFCs in the scale from micro materials to macro systems by extracting, analyzing and summarizing valid information from current findings, and look forward to future research and development directions.