Development of a Durable PEMFC Startup Process by Applying a Dummy Load

Abstract

Various polymer electrolyte membrane fuel cell (PEMFC) startup procedures were tested to explore possible techniques for reducing performance decay and improving durability during repeated startup–shutdown cycles. The effects of applying a dummy load, which prevents cell reversal by consuming the air at the cathode, on the degradation of a membrane electrode assembly were investigated via single-cell experiments. Electrochemical techniques, including measurement of polarization curves, electrochemical impedance spectroscopy, cyclic voltammetry, and linear sweep voltammetry, were employed to investigate the degradation of the PEMFCs. The results showed that application of a dummy load during the startup procedure significantly reduced the performance decay, the decrease in the electrochemically active surface area, and the increase in charge-transfer resistance (Rct) , which resulted in a dramatic improvement in durability. Our results suggest that starting up PEMFCs while applying a dummy load is an effective method for mitigating performance degradation caused by cell reversal under a repetition of unprotected startup cycles.

A review on performance degradation of proton exchange membrane fuel cells during startup and shutdown processes: Causes, consequences, and mitigation strategies

“…As shown in several operating parameters [33][34][35][36][37][38][39] that can have an impact on the degradation rate of PEMFCs under startup and shutdown cycles, including cathode humidity [37,38], cell temperature [33], application of a dummy load [35,36], and gas supply sequences [34]. The hydrogen/air interface during the startup and shutdown processes was mimicked by purging the anode and cathode channels with air after continuous air and hydrogen were supplied.…”

“…After the start/stop cycles, the relative number of particles with a diameter ≤2.5 nm declined from 57.20% in a fresh MEA to 1.92%. Cho et al combined the results of cross-sectional SEM and TEM to evaluate Pt/C degradation [33,34,36,38,39,45,59].…”

“…Another effective way to dispel residual gas is to introduce an auxiliary load (also called a dummy load). Kim et al [36] have investigated how applying a dummy load affects fuel cell degradation. Their results indicated that application of a dummy load during the startup procedure significantly reduced performance decay and loss of electrochemically active surface area, and increased charge-transfer resistance, which resulted in a dramatic improvement in durability.…”

Comparison of degradation behaviors for open-ended and closed proton exchange membrane fuel cells during startup and shutdown cycles

“…In comparison, the voltage of the closed cell decreased from 0.833 to 0.801 V, and the degradation rate was 0.0213 mV per cycle, almost two It is apparent that the cell performance decreased more seriously at high current density. The performance decay in the high current density region may be ascribed to the increased contact resistance at the CCM/GDL interfaces induced by carbon oxidation during the startup and shutdown cycles, resulting in worsening of the hydrosphere transport and mass diffusion [10][11][12]. By comparison of the degradation behaviors for open-ended and closed cells, it can be concluded that the performance decay of a closed fuel cell is less serious than that of an open-ended fuel cell while operating in frequent startup and shutdown cycles.…”

“…The group of the Fuel Cell Research Center at the Korea Institute of Science and Technology has been developing several methods to improve the durability of PEMFCs [10][11][12]. Kim et al [10] investigated the effects of applying a dummy load on the degradation of a single cell. Their results suggested that applying a dummy load in starting up PEMFCs was an effective way to mitigate performance degradation.…”