Date:	April 8, 1998

Objectives:

Complete potentiostatic performance evaluation on the 25 cm2 BCS fuel cell stack, made ,( 0.4mg/cm2, 20% Pt on C). Using standard current vs. Potential and Cyclic voltammetric sweeps, a fuel cell profile will be constructed.

Procedure Utilized:

Standard measurement practice of sweep the voltage from an open circuit potential to a minimum potential of 1.0V and back up to the open circuit potential. The will follow the voltage sweep file 4_01.txt or 4_05.txt. The sweep will be carried out as a Tafel sweep.

Environment:

Temperature-	70 degrees F

Barometer-	NA

Relative Humidity-	NA

Results & Conclusions:

The potentiostatic performance evaluation on the 25 cm2 BCS fuel cell stack was completed successfully at 50°C. The production water is faster at elevated temperatures and higher power constraints, as expected. There is a mass transport limitation happening as a result of a lack of oxidant during the potentiostatiic sweep as shown in the 4-8-98b plot of Voltage vs. Current.

The standard plating procedure, to be used for the electrolyzer electrodes, has been revised and is as follows;

Ti mesh of approximately (150 x 150), 0.1 mm diameter), and a solution dihydrogen hexachloroplatnic acid.

1.	Boil Ti mesh and boiling beads in acetone, for 1 hour, to remove any organic impurities.

2.	Boil Ti mesh and boiling beads in 1 molar hydrochloric acid for a period of 60 minutes.

3.	Oven dry the Ti Mesh for 2 hours at 105°C.

4.	Place the 1g dihydrogenchloroplatnic acid into a solution of 1M hydrochloric acid and dissolve acid.

5.	In a clean beaker with no dihydrogenchloroplatnic acid in it, boil Ti mesh and boiling beads in 1 molar hydrochloric acid for a period of 30 minutes.

6.	Remove the Ti mesh from the hydrochloric bath, attach to Platnium wire electrode holders and immedately place in HCl bath with the dihydrogenchloroplatnic acid dissolved in it, and connect the positive end of a power supply to the mesh and then connect the negative end of the other piece of Ti and submerse in the solution. Note-use caution to prevent the submersion of the non-platnium wire into the solution, as it will contaminate the whole solution.

7.	The platinum will be deposited gavanostatically by passing a current of approximately 1-5 mA per cm2 for a period of 6 hours.

8.	The terminals will be changed, i.e. the mesh connected to the positive terminal will be moved to the negative terminal and the negative mesh will be moved to the positive terminal. (Reverse the polarity on the electrodes)

9.	After the platinum has been deposited, an approximation of the amount will be made based on the weight of the electrodes after the deposition. Then the electrodes will be treated with a Nafion electro catalyst.

10.	The electro catalyst will be a ,5% by weight with an equivlent weight of 1100, Nafion solution that will be brushed directly onto the Ti mesh after Platnium deposition.

11.	The electrodes will then be placed in an oven and dryed for a period of 1 hour . (The Nafion solution is sintered at a temperature of 100°C.)

12.	The process will be continued until the electrode has accumulated an approximate weight of 0.8 - 1.0 mg/cm-2 of the Nafion catalyst.

Nafion Membrane Preparation

1.	The membrane material is cleaned according to standard procedure.

a.	Place the Nafion membrane in 3% H2O2 and boil solution for a period of 30 min.

b.	Place the membrane in milipore water and boil for a period of 60 min.

c.	Move the membrane to a 10-15% solution of Nitric acid and boiled for a period of 30 min.

d.	Place the membrane in milipore water and boil for a period of 60 min.

e.	Place the membrane in milipore water and boil for a period of 30 min prior to pressing.

2.	The electrodes and membrane are then pressed for a period of 90 seconds at 1 metric ton and 135°C.*

3.	The assembly is then placed into the test fixture.

*Please note that the electrode do not need to be pressed to the membrane as the mechanical pressure of the fixture alone is capable of holding the required pressure.