Toughened Membrane/Catalyst Layer Interface with Mechanical Nano-Fastener for Hydrocarbon Membrane Based Polymer Electrolyte Membrane Fuel Cell

Abstract

Polymer electrolyte fuel cells (PEMFCs) have been spotlighted as one of the promising eco-friendly energy technologies for stationary and automotive applications owing to zero CO2 emission, high energy density and moderate operation conditions. In this technology sector, polymer electrolyte membrane, one of the key components of PEMFC, has been intensely studied for several decades. Conventionally,perfluorinated sulfonic acid (PFSA) membranes like Nafion are used due to their high proton conductivity and mechanical stability. However, their high cost has been pointed out as a significant drawback interrupting mass commercialization of fuel cell electric vehicle. In this regard, hydrocarbon (HC) membranes, as cheaper alternatives, have been intensively studied in replacing PFSA membrane. However, until now, the challenge in adopting cost-effective HC membrane for PEMFCs has been the poor interfacial adhesion between catalyst layers (CLs) and HC membrane, which causes the membrane to delaminate easily, losing efficiency with use. Here, we present scalable mechanical nano-faster featured by three-dimensional interlocked interfacial structure between HC membrane and PFSA-based CL as a novel strategy to tackle the interfacial issue. It is realized by forming nano-porous skins on the both side of HC membrane and successively fiiling the pores with PFSA ionomer with scalable wet coating methods. The interlocking interface tightly binds the HC membrane and CL owing to its highly-interlocked ball and socket joint structure. The interfacial adhesion is dramatically enhanced by 37-fold with the nano-fastener. The membrane electrode assembly (MEA) with the three-dimensional interlocking interface exhibits 17 times higher durability than that with flat interface, paving a way to realize highly robust and cost-effective HC membrane-based PEMFCs for automotive use.