Development of an FCV with a New FC Stack for Improved Cold Start Capability 2010-01-1093
To promote widespread use of fuel cell vehicles (FCVs), further
improvement of cold start capability is required for operation in
various extreme temperature regions all over the world.
Sub-freezing, cold start issues of fuel cells must be resolved
through gaining a better understanding of the physical phenomena
taking place in a cell during cold start and by elucidating the
mechanisms hindering cold startup.
Nissan has improved its understanding of the physical phenomena
occurring in a fuel cell (FC) during cold startup by a
laboratory-scale FC experiment at subfreezing temperatures and a
numerical calculation that expresses various transport processes in
a fuel cell, including those of the reactant gases, water,
electrons and heat. The results have identified several necessary
conditions for mass transport in a cell during cold startup and the
factors that limit and govern the phenomena involved. For example,
the ice formation rate in the cathode catalyst layer, which has a
pronounced effect on cold start performance, is substantially
influenced by the product water uptake potential and uptake rate of
the polymer membrane. It has also been found that the ice formation
rate varies significantly depending on the physical properties and
initial water content of the membrane, load, temperature and other
These findings have been used to improve fuel cell materials and
to develop a new 2008 model FC stack that possesses ample cold
start capability without having any negative impact on other
performance attributes such as durability. Test results obtained
with an improved X-TRAIL FCV equipped with this new stack have
verified its cold start capability from -20°C and driving
performance under subfreezing conditions at the Hokkaido Proving
Grounds in Japan.
Finally, this paper also touches on some issues that will arise
in the future in connection with demands for lower cost FCVs and
mentions possible approaches to resolving them.