The new stack makes several improvements over the old one.
Not only is the new stack smaller and lighter, it achieves an output density of 5.4 kilowatts per liter, compared with 3.5 kW per liter in the old. And crucially, the new stack is much less costly.
Engineers slashed the cost of producing the stack some 70 percent, Deputy Chief Engineer Ryotaro Shimizu said. This was done by reducing the number of cells to 330 from 370 and cutting the amount of precious metals used. The amount of platinum was cut 58 percent.
Additional savings came from a reduction in the cycle time required to make the cells, and by shaving two-thirds off the time needed to wrap the hydrogen fuel tanks in costly carbon fiber. Further gains will come from spreading the use of the stack to other vehicles.
Toyota is making the fuel cell stacks at it Honsha plant in Toyota City, but the Mirai has been added to mixed production on the same line as the Crown sedan at the Motomachi plant, eking further production synergies.
