Impacts of characteristics of carbon black comprising microporous layer on performance and durability of gas diffusion layer under newly developed accelerated stress tests

Abstract

The gas diffusion layer (GDL) is an essential component of a proton-exchange membrane fuel cell (PEMFC) that supplies reactant gases to catalysts by facilitating the discharge of water generated via electrochemical reaction. The GDL is primarily composed of a substrate and a microporous layer (MPL), of which the latter increases the specific contact area for electrochemical reactions with catalysts and forms a capillary pressure gradient within the GDL. The MPL primarily comprises carbon black and polytetrafluoroethylene. Carbon black is categorized into the main and additive carbon blacks. Additive carbon black is utilized to augment the specific surface area of the MPL. This study examines the effects of four GDLs with varying additive carbon black contents constituting 20%–30 % of the total carbon black content on the performance of PEMFCs. In addition, the effects of the MPL characteristics on the durability of the GDL is investigated systematically, particularly in relation to carbon corrosion and freeze/thaw conditions. Furthermore, the deterioration in the performance and properties of the GDL are investigated via an acidic solution immersion accelerated stress test.