Fig. 2

Design of LCFCs stack. a Effect of single cell numbers of LCFCs on open-circuit voltage in separate LCFCs unit and LCFCs output voltage (=PEMEC input voltage) in the integrated device at 20 °C, respectively; the blue broken line marks the onset applied voltage value of 0.72 V in PEMEC. b Polarization curve in separate PEMEC unit at 20 °C; the black line is the experimental I–V curve in a PEMEC, and the red broken line is to determine the onset applied voltage in PEMEC. c Voltage–current plots in separate LCFCs unit with different total electrode area at 20 and 85 °C, respectively; d Voltage–current plots in separate LCFCs unit with electrode area of 12 cm² at different running temperatures