Fuel cell assembly having long life characteristics
View Patent ↗An example fuel cell assembly includes a separator plate. Non-porous and hydrophobic flow field layers are associated with the separator plate. An electrolyte retaining matrix comprises silicon carbide powder and has a mean particle size of about 3 microns and a thickness of about 0.05 mm Hydrophilic substrates are associated with catalyst layers. The hydrophilic substrates are about 70% porous and have a void volume that is about 40% filled with transferable phosphoric acid in an initial condition. A condensation zone cools a vapor passing from the assembly to less than about 140° C.
1. A fuel cell assembly, comprising:
a separator plate;
a first non-porous and hydrophobic flow field layer associated with the separator plate;
a second non-porous and hydrophobic flow field layer associated with the separator plate;
an electrolyte retaining matrix comprising silicon carbide powder having a mean particle size of about 3 microns and a thickness of about 0.05 mm;
a cathode catalyst layer;
an anode catalyst layer;
hydrophilic substrates associated with the catalyst layers, the hydrophilic substrates being about 70% porous and having a void volume that is about 40% filled with transferable phosphoric acid in an initial condition; and
a condensation zone that cools a vapor passing from the assembly to less than about 140° C.
2. The assembly of claim 1 , wherein the hydrophilic substrates have a thickness of about 0.46 mm and the initial transferable phosphoric acid content of two hydrophilic substrates is less than about 45 mg/cm 2 .
3. The assembly of claim 1 , wherein the hydrophilic substrates have a thickness of about 0.37 mm and the initial transferable phosphoric acid content of two hydrophilic substrates is less than about 35 mg/cm 2 .
4. The assembly of claim 1 , wherein the hydrophilic substrates have a thickness of about 0.25 mm and the initial transferable phosphoric acid content of two hydrophilic substrates is less than about 25 mg/cm 2 .
5. The assembly of claim 1 , wherein the electrolyte retaining matrix provides a reaction rate with phosphoric acid of less than about 0.010 mg/khr-cm 2 .
6. The assembly of claim 1 , wherein the condensation zone provides an evaporative phosphoric acid loss rate of less than about 0.27 mg/khr-cm 2 .
7. The assembly of claim 6 , wherein the condensation zone provides an evaporative phosphoric acid loss rate of less than about 0.17 mg/khr-cm 2 .
8. The assembly of claim 1 , wherein the flow field layers provide an acid absorption rate of less than about 0.10 mg/khr-cm 2 .