Low-cost FC Stack Concept with Increased Power Density and Simplified Configuration: Utilizing an Advanced MEA with Integrated Molded Frame

摘要

In 2006, Nissan began limited leasing of the X-TRAIL FCV equipped with their in-house developed FuelrnCell (FC) stack. Since then, the FC stack has been improved in durability, cold start-up capability, cost and size with the aimrnof promoting full-scale commercialization of FCVs. However, reduction of cost and size has remained a significantrnchallenge because limited mass transport through the membrane electrode assembly (MEA) has made it difficult to increasernthe rated current density of the FC. Furthermore, it has been difficult to reduce the variety of FC stack components due to therncomplex stack configuration. In this study, improvements have been achieved mainly by adopting an advanced MEA tornovercome these difficulties. First, the adoption of a new MEA and separators has improved mass transport through the MEArnfor increased rated current density. Second, an integrated molded frame (IMF) has been adopted as the MEA support. Onernadvantage of the IMF is its simplified structure and production process, reducing the MEA cost. Another advantage of thernIMF is that its flexibility for forming structural shapes which has been utilized to build insulating side walls (ISWs) aroundrnthe FC stack. Third, the FC stack structure has been simplified by elimination of a FC stack enclosure and adoption of arnsingle–row configuration which have been enabled by ISWs. As a result, the power density of the new FC stack has beenrnincreased to 2.5 kW/L, which is 30% higher than that of the previous 2008 model. It is estimated that the mass productionrncost of the new FC stack can be halved to nearly meet the target of the DOE Hydrogen Program. With further improvementsrnsuch as higher current density and lower catalyst loading, FCVs will be compact and affordable enough for ordinaryrnconsumers at the full-scale commercial stage.