Development of Fuel Cell Stack Durability based on Actual Vehicle Test Data: Current Status and Future Work

Nissan began developing a fuel cell vehicle (FCV) in 1996 and has participated in fleet programs in the USA (CaFCP) and in Japan (JHFC) since 2001 to promote FCV development and to educate the public on the benefits of FCVs. The X-TRAIL FCV (latest model) is equipped with various new technologies, including a fuel cell stack that was engineered in-house. The X-TRAIL FCV has evolved from a test vehicle in 2002 to today’s model, which provides the utility and conventional conveniences consumers would demand. The cruising range, acceleration performance and maximum speed are competitive with existing gasoline vehicles. However, to enable commercialization of FCVs, further improvements in performance and durability as well as reduction in costs will be necessary. Therefore, Nissan is investigating several different approaches for reducing cost and improving durability and performance.

This paper describes the durability of the fuel cell stack on the X-TRAIL FCV. Stack durability was estimated from the results of durability tests conducted with power train test benches. Stack performance degradation is considered in terms of three factors--start-stop, load cycling and high potential (idling)--which might be the main causes of the performance decline. Each degradation ratio is discussed in detail. The accuracy of the stack life estimation is also described on the basis of a comparison of FCV test data obtained on public roads, including proving ground and durability test data. A new fuel cell stack is now being developed, aimed at achieving lower cost, higher performance and greater durability. The measures taken to improve the durability of the new stack are also described.