Review of molten carbonate-based direct carbon fuel cells

Abstract

Direct carbon fuel cell (DCFC) is a promising technology with high energy efficiency and abundant fuel. To date, a variety of DCFC configurations have been investigated, with molten hydroxide, molten carbonate or oxides being used as the electrolyte. Recently, there has been particular interest in DCFC with molten carbonate involved. The molten carbonate is either an electrolyte or a catalyst in different cell structures. In this review, we consider carbonate as the clue to discuss the function of carbonate in DCFCs, and start the paper by outlining the developments in terms of molten carbonate (MC)-based DCFC and its electrochemical oxidation processes. Thereafter, the composite electrolyte merging solid carbonate and mixed ionic–electronic conductors (MIEC) are discussed. Hybrid DCFC (HDCFCs ) combining molten carbonate and solid oxide fuel cell (SOFC) are also touched on. The primary function of carbonate (i.e., facilitating ion transfer and expanding the triple-phase boundaries) in these systems, is then discussed in detail. Finally, some issues are identified and a future outlook outlined, including a corrosion attack of cell components, reactions using inorganic salt from fuel ash, and wetting with carbon fuels.

Carbon derived from treated rice husk as fuel for direct carbon fuel cells

“…At present, adding carbonate or other additives seems to be a feasible solution, which can effectively promote the extension of the three‐phase interface of the reaction. However, it will also be accompanied by severe corrosion of the collector and electrolyte 57 . There is a challenge to improving the long‐term stability of the cell.…”

“…However, it will also be accompanied by severe corrosion of the collector and electrolyte. 57 There is a challenge to improving the long-term stability of the cell.…”

Valorization of Exhausted Olive Pomace for the Production of a Fuel for Direct Carbon Fuel Cell

“…In this sense, a solid composite electrolyte composed of a molten salt phase, such as mixed carbonates, and an oxygen ion-conducting porous solid phase, such as samarium doped ceria (SDC), has been employed firstly for SOFCs and then adopted for DCFCs. The conductivity of this kind of composite electrolytes in an intermediate temperature (IT) range of 400 to 700 • C is around 10 −2 to 1 S m −1 much higher than a conventional solid electrolyte in a solid oxide fuel cell and a molten electrolyte in a molten carbonate fuel cell (MCFC) [27]. The high conductivity of such a composite electrolyte has been explained by the enhancing effect of the co-ionic conduction in the two phases.…”

Fuel Cell Types, Properties of Membrane, and Operating Conditions: A Review

“…The Li-Na carbonate has often been used as an electrolyte in MCFC to substitute the Li-K carbonate. Nevertheless, there may be a risk of a rapid decrease in cell voltage with Li-Na carbonate at atmospheric pressure and low temperature (≤600 • C) because of the relatively low solubility of oxygen in this eutectic [61].…”

“…The carbonate accelerates ion transfer as a medium or is a catalyst for carbon oxidation and gasification reaction with a producing power >1 MW [61]. The overall reaction is exo-energetic.…”