A Proton-Conducting In[sup 3+]-Doped SnP[sub 2]O[sub 7] Electrolyte for Intermediate-Temperature Fuel Cells

Nagao, Masahiro; Takeuchi, Akihiko; Heo, Pilwon; Hibino, Takashi; Sano, Mitsuru; Tomita, Atsuko

doi:10.1149/1.2159298

Cited by 151 publications

(167 citation statements)

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“…4, Sn 0.9 In 0.1 P 2 O 7 yielded a 1.061.32 times higher conductivity and a 0.03 eV lower activation energy for H 2 O-than for D 2 O-containing atmospheres. 18) According to the non-classical 25) or semi-classical H/D isotope effect, 26) when dissociation of the OH bond is a rate-determining step for proton conduction, the activation energy for D + is higher than that for H + by a difference in zero-point energy of 0.05 eV, which is near the difference in activation energy shown above. It is thus proposed that protons migrate via dissociation of hydrogen bonds with oxide ions in the P 2 O 7 units (hopping mechanism).…”

Section: Proton Conduction In Acceptor-doped Snp 2 Omentioning

confidence: 92%

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Intermediate-temperature proton conductors and their applications to energy and environmental devices

Hibino

2011

J. Ceram. Soc. Japan

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The development of proton conductors has proceeded rapidly in recent years. A number of organic or inorganic materials show proton conductivities of ³10 ¹2 S cm ¹1 at temperatures below 100°C. However, although there is great current demand for proton conductors capable of operating in the temperature range of 100400°C in practical applications, very few materials that can satisfy this demand have been reported to date. Acceptor-doped SnP 2 O 7 are promising candidate materials because their proton conductivities reach >10 ¹1 S cm ¹1 in the temperature range of interest. This paper presents an overview of the current status of acceptor-doped SnP 2 O 7 , highlighting the mechanism and kinetics of proton conduction and the development of electrochemical devices using these materials. New insights for proton insertion and conduction are proposed that use electrochemical techniques. Two approaches to designing SnP 2 O 7 -based composite electrolytes with good mechanical properties have also been developed for different operating temperatures. In addition, the benefits of intermediate-temperature operation using these materials are discussed in terms of practical applications, especially in fuel cells, exhaust sensors, and solid catalysts.

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Section: Proton Conduction In Acceptor-doped Snp 2 Omentioning

confidence: 92%

“…13) Interestingly, the proton conductivity of SnP 2 O 7 could be increased to ³10 ¹1 S cm ¹1 by the substitution of low valency cations, including In 3+ , 18) Al 3+ , 19) Mg 2+ , 20) Sb 3+ , 21) Sc 3+ , 22) and Ga 3+ 23) for part of the Sn 4+ cations. This conductivity value is sufficiently high for good performance of electrochemical devices.…”

Section: ¹1mentioning

confidence: 99%

Intermediate-temperature proton conductors and their applications to energy and environmental devices

Hibino

2011

J. Ceram. Soc. Japan

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“…5 Sn 0.92 Sb 0.08 P 2 O 7 was prepared in a similar manner to that reported previously. 6 A total of 0.04 g of poly(tetrafluoroethylene) (PTFE) powder was added to 1.00 g of Sn 0.92 Sb 0.08 P 2 O 7 powder, followed by kneading with a mortar and pestle, and then cold-rolling to a thickness of 150¯m using a laboratory rolling mill. The cathode used was Pt/nitrogen-doped graphene, which exhibited higher activity for the oxygen reduction reaction and better thermal stability, compared to conventional Pt/C cathodes.…”

Section: ¹2mentioning

confidence: 99%

A Direct Urine Fuel Cell Operated at Intermediate Temperatures

2014

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Direct utilization of urine in fuel cells is a promising technology for conversion into electricity. Here, we report the design of anode materials for high-temperature direct urine fuel cells and the performance of a fuel cell with an optimized anode at 300°C. The resultant peak power densities reached 16.7 mW cm ¹2 for urine and 26.5 mW cm ¹2 for urea.Human urine can be regarded as an alternative energy source to fossil fuels because it is an abundant waste product that includes urea, creatinine, uric acid, and ammonia as hydrogen carrier compounds. In particular, urea contains a gravimetric hydrogen content of 6.7 wt %, 1 which constitutes a high energy density when used as a fuel. In addition, this substance is nonflammable and nontoxic in contrast to other hydrogen carrier chemicals. On the other hand, a large amount of digestion gas is produced by anaerobic digestion in sewerage disposal plants; however, ca. 30% of the mass of digestion gas is incinerated without being used.In this study, we have developed a direct urine fuel cell using the unused digestion gas as a heat source. Operation of a fuel cell at elevated temperatures makes the anode catalyst more active to reductants in the urine, which allows for the low polarization resistance of the anode. Furthermore, there is the possibility that such reductants are internally reformed to more reactive compounds over the anode, which further reduces the polarization resistance. Two types of fuel cells have been proposed for direct urine utilization in fuel cells: alkaline membrane 2,3 and microbial fuel cells. 4 However, they are both operated at low temperatures with respective power densities of 4 mW cm ¹2 (alkaline membrane fuel cell) and 5 mW m ¹2(microbial fuel cell), which are much lower than those of hydrogen-powered fuel cells. As the production cost of human urine is substantially close to zero, high power density may not necessarily be required for this type of fuel cell. Nevertheless, further increase in the power density would enhance the position of direct urine fuel cells as the preferred energy conversion devices for practical applications.Hydroxide ion conductors and cathodes were important substances in this study. The hydroxide ion conductor used was Sn 0.92 Sb 0.08 P 2 O 7 because this material possesses a hydroxide ion conductivity of ca. 0.05 S cm ¹1 in the temperature range above 0.01 S cm ¹1 between 100 and 300°C. 5 Sn 0.92 Sb 0.08 P 2 O 7 was prepared in a similar manner to that reported previously. 6 A total of 0.04 g of poly(tetrafluoroethylene) (PTFE) powder was added to 1.00 g of Sn 0.92 Sb 0.08 P 2 O 7 powder, followed by kneading with a mortar and pestle, and then cold-rolling to a thickness of 150¯m using a laboratory rolling mill. The cathode used was Pt/nitrogen-doped graphene, which exhibited higher activity for the oxygen reduction reaction and better thermal stability, compared to conventional Pt/C cathodes. This electrode powder was synthesized according to a previously reported procedure.7 Pt/C, Ru/C, Ni/C, Pd/C, and Rh/...

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“…For this reason, extensive research has been conducted to develop the protonconducting ceramic fuel cell (PCFC) because of the relatively high proton-conductivity in the temperature region. [1][2][3][4][5] Hydrogen membrane fuel cell (HMFC), which was firstly proposed by Ito et al, consists of an ultrathin proton conducting ceramic electrolyte supported on a dense hydrogen permeable metal anode. [6][7][8] The cell facilitates efficient power generation, giving 900 mW cm ¹2 at 500°C, 7 since reduced electrolyte thickness can significantly decreases the ohmic loss at lower temperatures.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Analysis of Hydrogen Membrane Fuel Cells with Amorphous Zirconium Phosphate Thin Film Electrolyte

et al. 2014

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An electrochemical analysis was conducted with respect to a hydrogen membrane fuel cell (HMFC) comprising proton-conducting, amorphous zirconium phosphate, a-ZrP 2.5 O 8.9 H 1.3 , thin film electrolyte supported on a dense Pd anode. The HMFC gave rise to an OCV of 1.0 V, but the maximum power density was limited and was about 1 mW cm −2 at 400°C. The impedance spectroscopy revealed that the interfacial polarizations were decreased by two orders of magnitude when the cell configuration was changed from the fuel cell setup to the hydrogen concentration cell with an anode symmetric configuration. These results indicated that the polarization losses at the solid-solid anode interface are not a main contribution to the voltage loss of the HMFC. The large cathode polarization might be attributed to the lessened conductivity of amorphous zirconium phosphate electrolyte thin film formed on a precious metal electrode.

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A Proton-Conducting In[sup 3+]-Doped SnP[sub 2]O[sub 7] Electrolyte for Intermediate-Temperature Fuel Cells

Cited by 151 publications

References 21 publications

Intermediate-temperature proton conductors and their applications to energy and environmental devices

Intermediate-temperature proton conductors and their applications to energy and environmental devices

A Direct Urine Fuel Cell Operated at Intermediate Temperatures

Electrochemical Analysis of Hydrogen Membrane Fuel Cells with Amorphous Zirconium Phosphate Thin Film Electrolyte

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