Molten carbonate fuel cells electrolyte

Arendt, R.H. Alternate matrix materials for molten carbonate fuel cell electrolyte structures. J. Electrochem. Soc. 1982, 129 (5), 979-983. 

Baumgartner, C.E. DeCarlo, V.J. Glugla, P.G. Grimaldi, J.J. Molten carbonate fuel cell electrolyte structure fabrication using electrophoretic deposition. J. Electrochem. Soc 1985, 132 (1), 57-63. 

Mirahmadi A, Akbari H (2012) A noble method for molten carbonate fuel cells electrolyte manufacturing. J Solid State Electrochem 16 931-936... 

Molten Carbonate Fuel Cell. The electrolyte ia the MCFC is usually a combiaation of alkah (Li, Na, K) carbonates retaiaed ia a ceramic matrix of LiA102 particles. The fuel cell operates at 600 to 700°C where the alkah carbonates form a highly conductive molten salt and carbonate ions provide ionic conduction. At the operating temperatures ia MCFCs, Ni-based materials containing chromium (anode) and nickel oxide (cathode) can function as electrode materials, and noble metals are not required. 

Molten Carbonate Fuel Cell The electrolyte in the MCFC is a... 

The PAFC is, however, suitable for stationary power generation, but faces several direct fuel cell competitors. One is the molten carbonate fuel cell (MCFC), which operates at "650°C and uses an electrolyte made from molten potassium and lithium carbonate salts. Fligh-teinperature operation is ideal for stationary applications because the waste heat can enable co-generation it also allows fossil fuels to be reformed directly within the cells, and this reduces system size and complexity. Systems providing up to 2 MW have been demonstrated. 

High-temperature molten-carbonate fuel cells (MCFCs). The electrolyte is a molten mixture of carbonates of sodium, potassium, and lithium the working temperature is about 650°C. Experimental plants with a power of up to... 

Molten carbonate fuel cells use a mixture of lithium and potassium carbonate as an electrolyte and have an OT of 630 to 650°C. 

For natural-gas-fuelled CHP plants, the same line of argumentation holds as for the stationary use of hydrogen from biomass. It is more reasonable to use natural gas directly than to convert it to hydrogen first and then to heat and electricity. High electrical efficiencies can be reached in the stationary sector by feeding natural gas to molten-carbonate fuel cells (MCFC) and solid-oxide fuel cells (SOFC). Molten-carbonate fuel cells have the added advantage of using C02 for the electrolyte (see also Chapter 13). 

Progress continues in fuel cell technology since the previous edition of the Fuel Cell Handbook was published in November 1998. Uppermost, polymer electrolyte fuel cells, molten carbonate fuel cells, and solid oxide fuel cells have been demonstrated at commercial size in power plants. The previously demonstrated phosphoric acid fuel cells have entered the marketplace with more than 220 power plants delivered. Highlighting this commercial entry, the phosphoric acid power plant fleet has demonstrated 95+% availability and several units have passed 40,000 hours of operation. One unit has operated over 49,000 hours. 

Molten Carbonate Fuel Cell The electrolyte in the MCFC is a mixture of lithium/potassium or lithium/sodium carbonates, retained in a ceramic matrix of lithium aluminate. The carbonate salts melt at about 773 K (932°F), allowing the cell to be operated in the 873 to 973 K (1112 to 1292°F) range. Platinum is no longer needed as an electrocatalyst because the reactions are fast at these temperatures. The anode in MCFCs is porous nickel metal with a few percent of chromium or aluminum to improve the mechanical properties. The cathode material is hthium-doped nickel oxide. 

Fuel cells are typically classified by the type of electrolyte. Apart from certain specialty types, the five major types of fuel cells are alkaline fuel cell (AFC), polymer electrolyte fuel cell (PEMFC), phosphoric acid fuel cell (PAFC), molten carbonate fuel cell (MCFC), and solid oxide fuel cell (SOFC). 

Molten carbonate fuel cells (MCFCs) are currently being developed for natural gas and coal-based power plants for electrical utility, industrial, and military applications. MCFCs are high-temperature fuel cells that use an electrolyte composed of a molten carbonate salt mixture suspended in a porous, chemically inert ceramic lithium aluminium oxide (LiAI02) matrix. Since they operate at extremely high temperatures of 650°C and above, non-precious metals can be used as catalysts at the anode and cathode, reducing costs. 

In the molten carbonate fuel cell, methane is used as the fuel. This cell runs at high temperatures and uses a molten mixture of lithium and potassium carbonates as electrolyte. In most such cells, the methane is reformed into hydrogen and carbon monoxide before reacting in the cell ... 

As a first example of the use of reaction mechanism graphs, consider the electrochemistry of molten carbonate fuel cell (MCFC) cathodes. These cathodes are typically nickel-oxide porous electrodes with pores partially filled with a molten carbonate electrolyte. Oxygen and carbon dioxide are fed into the cathode through the vacant portions of the pores. The overall cathodic reaction is 02 + 2C02 + 4e / 2C03=. This overall reaction can be achieved through a number of reaction mechanisms two such mechanisms are the peroxide mechanism and the superoxide-peroxide mechanism, and these are considered next. 

Molten carbonate fuel cell (MCFC)—Carbonate electrolyte with conventional metal catalyst. It can use coal gas and natural gas fuel, and is suited for 10 kW to 2 mW power plants. 

Note PAFC phosphoric acid fuel cell PEMFC proton exchange membrane fuel cell/polymer electrolyte membrane fuel cell MBFC microbiological fuel cell DMFC direct methanol conversion fuel cell AFC alkaline fuel cell MCFC molten carbonate fuel cell SOFC solid oxide fuel cell ZAFC zinc air fuel cell. 

Molten carbonate fuel cell (MCFC) working at about 650°C with a mixture of molten carbonates (Li2C03/K2C03) as electrolyte, conducting by the C03= anion, both of them being high-temperature fuel cells. 

The molten carbonate fuel cells employ LijCOj-f CC (62.38 mol.%) electrolytes, porous Ni alloy, and lithiated nickel oxide as anodes and cathodes at an operating temperature of 723 K. The half-cell reactions of each side are, respectively... 

The electrolyte in this fuel cell is generally a combination of alkali carbonates, which are retained in a ceramic matrix of LiA102 [8], This fuel cell type works at 600°C-700°C, where the alkali carbonates form a highly conductive molten salt with carbonate ions providing ionic conduction. At the high operating temperatures in the molten carbonate fuel cell, a metallic nickel anode and a nickel oxide cathode are adequate to promote the reaction [9], Noble metals are not required. 

Molten carbonate fuel cells (MCFC), with alkali carbonate (in LiA102 matrixes) electrolyte, conduct C032 -anions, generated at an 02/C02 exposed cathode to electro-oxidise H2 at the anode and at high temperatures. 

Molten carbonate fuel cells use a mixture of carbonates that are liquid at operating temperature—600°C to 650°C. MCFC, like SOFC, operates at a higher temperature than the PEMFC does it does not require a fuel reformer and it can be operated with a hydrogen-rich fuel. The MCFC s liquid electrolyte means more handling issues. It does not have the ability to be pressurized. The MCFC could serve a niche market of data centers and hospitals. FuelCell Energy has recently made a commercial offering of MCFCs. These fuel cells will probably not have the same market penetration potential as SOFCs and thus would likely have little or no impact as a transition strategy for H2 use. 

Molten carbonate fuel cell technology was developed based on the work of Bauers and Ehrenberg, Davy tan, and Broers and Ketelaar in the 1940s [8], The electrolyte is a molten salt such as sodium carbonate, borax, or cryolite. This type of fuel cell requires a high temperature to keep the electrolyte in a molten state. The following 30-40 years saw great successes, with the development of MCFCs and MCFC stacks that could be operated for over 5000 hours. 

Several types of fuel cells have been developed and are classified according to the electrolytes used alkaline fuel cells, molten carbonate fuel cells, phosphoric acid fuel cells (PAFCs), PEMFCs, and solid oxide fuel cells (SOFCs). As shown in Figure 1.3, the optimum operation temperatures of these fuel cells are different, and each type has different advantages and disadvantages. 

Chapters I to III introduce the reader to the general problems of fuel cells. The nature and role of the electrode material which acts as a solid electrocatalyst for a specific reaction is considered in chapters IV to VI. Mechanisms of the anodic oxidation of different fuels and of the reduction of molecular oxygen are discussed in chapters VII to XII for the low-temperature fuel cells and the strong influence of chemisorhed species or oxide layers on the electrode reaction is outlined. Processes in molten carbonate fuel cells and solid electrolyte fuel cells are covered in chapters XIII and XIV. The important properties of porous electrodes and structures and models used in the mathematical analysis of the operation of these electrodes are discussed in chapters XV and XVI. 

Using a cell that was designed along the lines of a molten carbonate fuel cell (Fig. 22), the removal rates of SOj varied from 78 7o at 600 ppm of SO at the cathode to 24% at 2100 ppm of at the cathode. The same authors [103] also reported an improvement over their earlier study by using a ternary eutectic of lithium, potassium, and sodium sulfates as the electrolyte together with Li20-9Cr03 electrodes, which were found to be stable in the molten electrolyte. 

Lim and Winnick [110] examined removal of H2S from a simulated hot coal-gas stream fed to the cathode while elemental sulfur gas was evolved at the anode. This process was performed in a cell that was similar in construction to a molten carbonate fuel cell (Fig. 23). The electrolyte was a mixture of Na2S and Li2S retained in a porous inert matrix material (MgO). The cathodic reaction involved the two-electron reduction of hydrogen sulfide to hydrogen (information on the equilibrium potential for H2S reduction can be obtained from [111] ... 

A fuel cell cycle employing carbonate ions penetrating a solid matrix electrolyte at high temperatuures is schematically illustrated in Fig. 3.16. It is aimed at stationary applications and promises high efficiency. The electrode reactions for this electridty-produdng molten carbonate fuel cell (MCFC) are... 

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