Electrochemical characterisation, consisting of current-voltage (IV) curves and galvanostatic impedance spectroscopy (GEIS), was run on each cell configuration after the conditioning procedure and after the stability test. IV curves were produced using a series of 24 × 60 s galvanostatic hold steps between 0.005 and 1 A cm -2 with a data acquisition rate of 1 pt s -1 . The last 10 data points from each galvanostatic hold step were averaged to generate each data point for the IV curve. Starting at 0.1 A cm -2 , GEIS was run after each hold at the corresponding DC setpoint with an AC amplitude of ≥ 10% DC from 50 kHz to 100 Hz with 13 points per decade to measure the high frequency resistance (HFR) at each current density. The HFR, which is the sum of the membrane resistance (Rmemb) and the electronic resistance (sum of contact resistances between flow-fields and PTLs and bulk PTL resistances, Rel) was estimated from the GEIS data by taking the value of real impedance at high frequency where imaginary impedance was equal to zero. To identify the contribution of various voltage losses, polarisation curves were corrected by the HFR (i.e., iR corr.).