However, the fuel cell shows differ

However, the fuel cell shows different performance degradation phenomenon at two operatingconditions, i.e. at steady state condition, the performance degradation rate will increase at the early operation stage (from 48 h to 658 h in Fig. 2(a)), and then decrease at the end of the fuel cell lifetime, while the PEM fuel cell performance degradation is still clear at the end of its lifetime at dynamic current density condition (shown in Fig. 2(b) from 666 h to 1016 h).