Quick crossover current measurement of a polymer electrolyte fuel cell stack with and without cell voltage terminals

Crossover current (COC) measurement is an important diagnostic method for a polymer electrolyte fuel cell. Although a COC measurement method for single cells has already been established, a considerable amount of time is required to individually measure the COC of cells in a stack. Herein, we proposed two new methods to measure the COC of all cells in a stack quickly without the risk of electrode deterioration owing to overvoltage, even in a stack with a large COC difference between the cells. The first method was applied to a stack with cell voltage terminals in which parallel resistors are connected to each cell, and the COC of each cell is simultaneously measured via current scanning. The other method was applicable to a stack without cell voltage terminals in which the COC is obtained from the open-circuit voltage decay characteristics of the stack after applying direct voltage instantaneously. The measurement accuracy of these two methods was verified using a layered stack comprising four cells with different electrolyte membrane thicknesses.