Development of a measurement technique for current-density in PEFC using planar surface coil as a NMR signal detector (2nd Report, One-Dimensional measurement of current-density generating in PEFC at case of current flowing in lamination direction)

To improve a performance of PEFC, it is necessary to maintain high current density generating in the whole area of a fuel cell. Spatial distribution of the electric current generating in PEFC can be measured from the frequency shift of Nuclear Magnetic Resonance (NMR) signal received by planar surface coils inserted into PEFC. Applying this technique, the frequency shift of NMR signal in the PEFC which sent power generation current in the lamination direction was measured. In this study, two kinds of Polymer Electrolyte Membrane (MEA) were used. One was MEA which applied the platinum catalyst to an area of 50 mm × 50 mm. The other was MEA with platinum catalyst of its half area. The distributions of the frequency shift of NMR signal in PEFCs used two MEAs were measured, and the spatial distributions of current density generating in PEFCs were obtained. The result of MEA with Pt catalyst of 50 mm × 50 mm area showed uniform current distribution in the whole area. On the other hand, the results of MEA with Pt catalyst of the half area showed two areas, the region of uniform current, and the region of zero current. These measurement results were in agreement with the theoretical-analysis results of magnetic field in PEFC. The uncertainly of this measurement technique was evaluated from the obtained results.