Liquid-liquid fuel cell systems having flow-through anodes and flow-by cathodes

A fuel cell stack assembly, comprising:

• a plurality of electrode pair assemblies arranged in an anode-cathode/anode-cathode configuration, wherein each electrode pair assembly is configured to receive and react with a liquid anolyte flowstream and a liquid catholyte flowstream and includes (i) a porous flow-through anode, (ii) a porous flow-by cathode confronting and spaced apart from the anode, and (iii) a central plenum interposed between the anode and the cathode, wherein the anolyte flowstream is configured to flowingly contact and substantially pass through the anode and into or out of the central plenum, and wherein the catholyte flowstream is configured to flowingly contact and pass adjacent to the cathode such that a nonflowing portion of the catholyte flowstream reacts at the cathode but does not substantially pass through the cathode and into the central plenum.

A fuel cell stack assembly, comprising:

• a plurality of electrode pair assemblies arranged in an anode-cathode/cathode-anode configuration, wherein each electrode pair assembly is configured to receive and react with a liquid anolyte flowstream and a liquid catholyte flowstream and includes (i) a porous flow-through anode, (ii) a porous flow-by cathode confronting and spaced apart from the anode, and (iii) a central plenum interposed between the anode and the cathode, wherein the anolyte flowstream is configured to flowingly contact and substantially pass through the anode and into or out of the central plenum, and wherein the catholyte flowstream is configured to flowingly contact and pass adjacent to the cathode such that a nonflowing portion of the catholyte flowstream reacts at the cathode but does not substantially pass through the cathode and into the central plenum.