Introduction

Polymer electrolyte fuel cells (PEFCs) offer many advantages, such as low operating temperature and a high power density. Taking these advantages, PEFCs have been paid much attention as a promising power source for transportation use and stationary use in recent years. SANYO has been developing PEFCs as an R & D project of NEDO under the New Sunshine Project from FY 1992.

In PEFCs, a precious metal, platinum is used as the electrode catalyst. Therefore, reducing the electrode catalj'st is one of the important subjects for practical application. We have developed an electrode with a new structure which has already reported')2), called "High ion conductive electrode". We have developed 1 kW class module (1st model, 200 cm2 x 20-cell module) with this unique electrode in last year. The output power density of more than 0.3 W/cm2 was achieved at a pressure of 3 atm and current density of 0.5 A/cm2 (this performance met the projected target) in this module, but the large voltage drop occurred when the air utilization was higher than 20 %. To solve this problem and to develop higher performance modules, we examined the cell components of the PEFC module, mainly concerning with air channel configuration of the gas separator and the current collector of the electrode.

In this paper, results of the study and the operating tests of 200 cm2 x 20-cell module (2nd model) and 200 cm2 x 36-cell module in which cell components were modified are described

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