Nissan announced that it has designed and developed its first in-house fuel cell stack, as well as a new 700 bar hydrogen storage system. The automaker had been using United Technologies stacks in earlier fuel cell prototypes.
The new technologies offer improved acceleration, performance and driving range.
Nissan’s fuel cell stack uses a newly developed thin separator. The separator is the component that separates the hydrogen and oxygen gases supplied to the individual cells and transfers the electricity produced to the next cell.
A fuel cell for a vehicle will likely use several hundred fuel cells connected in a stack in series to obtain the necessary voltage.
The new separator narrows the spacing between adjacent fuel cells (the cell pitch) connected in the stack by 40% compared to the previous stack from UTC used in the X-TRAIL FCV.
Nissan also integrated the plumbing components inside the stack case, and built into the case the peripheral control devices.
As a result, Nissan has increased power while reducing size. The new stack can be reduced in volume to approximately 60% of the previous stack while providing the same level of power.
Improvements to the electrode materials also more than double the service life of the new stack compared with the stack previously used. The new fuel cell stack also has an expanded temperature operating range.
A new 700 bar (10,000 psi) hydrogen storage cylinder increases vehicular hydrogen storage capacity by approximately 30% compared with the previous 350 bar (5,000 psi) cylinder without any change to the cylinder’s external dimensions. The increased storage extends the driving range of a fuel cell vehicle.
The new high-pressure hydrogen storage cylinder is made of an inner aluminum liner and an outer shell of several wound layers of a high-strength, high-elasticity carbon fiber.
Nissan began conducting FCV public-road tests in the US in 2001 and Japan in 2002. Nissan began leasing its X-TRAIL FCV to a limited number of customers, starting with oil refiner Cosmo Oil Co. in March 2004.
The current (2003) model of the X-TRAIL FCV (at right) with the UTC fuel cell stack and 350 bar storage has a top speed of 145 km/h (90 mph) and a range of some 350 km (218 miles).
Nissan will now begin in-vehicle testing of the new fuel cell stack to further improve its overall performance and reliability.