Impact of gas products around the anode on the performance of a direct carbon fuel cell using a carbon/carbonate slurry

Watanabe, Hirotatsu; Umehara, Daisuke; Hanamura, Katsunori

doi:10.1016/j.jpowsour.2016.08.122

Cited by 9 publications

(14 citation statements)

References 21 publications

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“…In addition to the gasification, char has been receiving an increasing amount of attention with regard to utilization in direct carbon fuel cells (DCFCs) . DCFCs can convert biochar into electricity without the need for gasification. − Although the development of this technology has been relatively slow, a recent review has pointed out that the field of DCFCs has been attracting an ever increasing amount of interest . Because the char has a potential role in different reaction processes, such as gasification and DCFCs, as described above, the chemical and physical characterizations of chars have become important.…”

Section: Introductionmentioning

confidence: 99%

X-ray Computed Tomography Visualization of the Woody Char Intraparticle Pore Structure and Its Role on Anisotropic Evolution during Char Gasification

Watanabe

2018

Energy Fuels

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X-ray computed tomography (CT) was used to visualize the intraparticle structure of woody biomass and its chars. Additionally, the impact of the intraparticle structure on gasification characteristics was investigated. The chars derived from ramin (hardwood) and Japanese cypress (softwood) were gasified under an O 2 /Ar atmosphere. X-ray CT was used to observe the intraparticle structure. As a result, X-ray CT performed well in visualizing relatively large pores of over 5 μm. The ramin chars had larger pores aligned along the transverse direction in comparison to Japanese cypress chars. The pores aligned along the grain direction were dominant in both chars. Although the gasification rate of both chars was similar, the impact of the anisotropic intraparticle structure originating from the nature of wood manifested in the evolution of the particle shape during gasification controlled by internal diffusion. This was due to large pores acting as gas transport pathways inside the chars. The gasification advanced along the transverse direction in the ramin chars and resulted in the formation of an ellipse shape, although the initial shape was a cylinder. On the contrary, in the Japanese cypress chars, the gasification progressed only along the grain direction and the cylindrical shape was maintained.

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Section: Introductionmentioning

confidence: 99%

X-ray Computed Tomography Visualization of the Woody Char Intraparticle Pore Structure and Its Role on Anisotropic Evolution during Char Gasification

Watanabe

2018

Energy Fuels

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“…The CO 2 and CO production rates during discharge were measured in the constant current discharge, and the theoretical production rates were also calculated. When carbon is consumed through electrochemical oxidation of carbon (reaction ), the CO 2 production rate during discharge is calculated as follows: where F is the Faraday constant (96 450 C/mol), V m is the molar volume of CO 2 , and I is the constant current flow, and details are provided elsewhere. , …”

Section: Methodsmentioning

confidence: 99%

“…15 The counter electrode (CE) and reference electrode (RE) were made from a circular gold plate (diameter of 13.5 mm and thickness of 0.5 mm) covered by a 100mesh gold and a gold sheet with a height of 10 mm and a width of 5 mm, respectively. The gas products at the reaction sites in the conventional DCFCs simply remained around the anode, 14 whereas these were released in press-type DCFC through the perforations as a result of their buoyancy. 15 A quartz reactor was heated using an electric furnace, and argon was introduced into the reactor compartment during heating.…”

Section: Methodsmentioning

confidence: 99%

“…Solid carbon is oxidized by CO 3 2− transported through a molten carbonate electrolyte from the cathode. Our previous studies revealed that gas products formed around the anode during discharge 14 and that these gas bubbles inhibited the formation of reaction sites. This lowered the performance of the conventional DCFC, in which the anode was inserted into the carbon/carbonate slurry.…”

Section: Introductionmentioning

confidence: 99%

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Impact of Mass Transfer in the Carbon/Carbonate-Packed Bed on the Power Output of a Press-Type Direct Carbon Fuel Cell

et al. 2019

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The power output of a press-type direct carbon fuel cell (DCFC) with the perforated anode pressed on the carbon/carbonate-packed bed was studied by correlation with impedance spectroscopy at different carbon loads. Image analysis of the solidified carbon/carbonate-packed bed showed that the filling ratio of carbon and the contact area between carbon and the anode linearly increased as the initial carbon load increased. The power output of the DCFC also increased with increasing the initial carbon load and became almost saturated at an initial carbon load of 3.0 wt %. This trend coincided with the anode side impedance spectra. At high current densities, the power output became unstable and a continuous discharge could not be achieved at an initial carbon content of 5.0 wt %. Although the press-type DCFC is designed to release gas products through its perforated anode, those products likely still remained around the anode at high current densities. Spaces between the carbon particles in the packed bed worked as a channel for ion diffusion. Therefore, gas products likely blocked this ion diffusion channel, narrowing with increasing the filling ratio of carbon. By linking the impedance spectra with the power output of the press-type DCFC, it was suggested that the ion diffusion process in the carbon/carbonate-packed bed played an important role for stable continuous discharge at high current densities.

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“…5) [104]. One investigation showed a noticeable increase in over-potential at a higher current density, owing to the mass transfer process being prevented, but it was easy for the released CO 2 gas to make contact with the carbon and ions at the anode again, with a long-term discharge recorded [105].…”

Section: Mechanismsmentioning

confidence: 99%

Review of molten carbonate-based direct carbon fuel cells

Cui

Gong

et al. 2021

Mater Renew Sustain Energy

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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.

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Impact of gas products around the anode on the performance of a direct carbon fuel cell using a carbon/carbonate slurry

Cited by 9 publications

References 21 publications

X-ray Computed Tomography Visualization of the Woody Char Intraparticle Pore Structure and Its Role on Anisotropic Evolution during Char Gasification

X-ray Computed Tomography Visualization of the Woody Char Intraparticle Pore Structure and Its Role on Anisotropic Evolution during Char Gasification

Impact of Mass Transfer in the Carbon/Carbonate-Packed Bed on the Power Output of a Press-Type Direct Carbon Fuel Cell

Review of molten carbonate-based direct carbon fuel cells

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