Advances in Mixed‐Reactant Fuel Cells

Abstract

The mixed‐reactant fuel cell (MRFC) is a new concept, in which a mixture of aqueous fuel and gaseous oxygen (or air) flows directly through a porous anode‐electrolyte‐cathode structure or through a strip‐cell with an anode‐electrolyte‐cathode configuration. These structures can be single cells or parallel stacks of cells and may be in a planar, tubular or any other geometry. Selectivity in the electrocatalysts for MRFCs is mandatory to minimize mixed‐potential at the electrodes, which otherwise would reduce the available cell voltage and compromise the fuel efficiency. MRFC offers a cost effective solution in fuel cell design, since there is no need for gas‐tight structure within the stack and, as a consequence, considerable reduction in sealing, manifolding and reactants delivery structure is possible. In recent years, significant advances have been made in MRFCs, using methanol as a fuel. This paper reviews the status of mixed reactant fuel cells and reports some recent experimental data for methanol fuel cell systems.

Single-Chamber Solid Oxide Fuel Cell Technology—From Its Origins to Today’s State of the Art

“…The term "single-chamber" has been introduced in 1999 by Hibino et al [6], one of the pioneers of SC-SOFC technology, and is generally used. But "one-chamber" [7], "single-compartment" [8], "mixed-gas" [9][10][11], "mixed-fuels" [12], "mixed-reactant" [1, 13,14] and "separator free" [15] fuel cells as well as "SOFCs with reaction-selective electrodes" [16] can also be found in the literature.…”

“…Thus, both the electrocatalytic activity and the selectivity of the electrodes lead to the generation of the OCV and electricity in SC-SOFCs. In addition to SOFCs, the single-chamber operating mode has so far also been demonstrated for alkaline fuel cells [17][18][19], direct-methanol fuel cells (mixed-reactant direct-methanol fuel cells, MR-DMFCs) [1, 13,[20][21][22][23], and microbial fuel cells [24]. MR-DMFCs combine the advantage of reduced explosion risks through operation on diluted methanol-air mixtures at low temperatures (e.g.…”

“…MR-DMFCs combine the advantage of reduced explosion risks through operation on diluted methanol-air mixtures at low temperatures (e.g. 90 °C) and of overcoming the problems of methanol cross-over and coupled low performance in conventional DMFCs [13]. Table 1 summarizes advantages and challenges of SC-SOFCs.…”

“…In the single-chamber operating mode, two types of catalytic reactions are expected to occur: (i) the heterogeneous catalysis of the fuel (partial oxidation) at the anode (12,13), and (ii) the selective electro-catalysis of fuel oxidation at the anode (1, 14) and oxygen reduction at the cathode (2): …”

“…Figure 3 shows a schematic representation of the operating principle of SC-SOFCs. On the anode catalyst, internal reforming of the hydrocarbon occurs via selective catalytic partial oxidation (12,13). A syngas consisting of hydrogen and carbon monoxide is formed which reacts electrochemically with oxygen ions at the anode (1,14).…”