An electrochemical cell stack comprises a plurality of electrochemical cell units, each comprising a cathode, an anode, and an electrolyte, and also comprises a plurality of interconnects. An interconnect is disposed between adjacent electrochemical cell units and defines a longitudinal channel having circumferential corrugations defined therearound. A fuel channel is defined between each anode and a respective adjacent interconnect, the fuel channel having fuel inlet and outlet. An oxidant channel is defined between each cathode and a respective adjacent interconnect, the oxidant channel having an oxidant inlet and outlet. The plurality of electrochemical cell units and interconnects include a first electrochemical cell unit, a first interconnect adjacent the first electrochemical cell unit, a second electrochemical cell unit adjacent the first interconnect, and a second interconnect adjacent the second electrochemical cell unit. The second interconnect is rotationally offset from the first interconnect about a longitudinal axis of the fuel cell stack.