New Chemical Systems for Solid Oxide Fuel Cells

In this paper we report the successful incorporation of borate and phosphate into CaMnO 3 and borate into La 1Ày Sr y MnO 3Àd . For CaMnO 3 , an increase in the electronic conductivity was observed, which can be correlated with electron doping due to the oxyanion doping favoring the introduction of oxide ion vacancies (as well as the higher valence of P 5+ compared to Mn 4+ in the case of phosphate doping). The highest conductivity at 800 C was observed for CaMn 0.95 P 0.05 O 3Àd , 43.0 S cm À1 , in comparison with 7.6 S cm À1 for undoped CaMnO 3 at the same temperature. For La 1Ày Sr y MnO 3Àd the conductivity suffers a decrease for all compositions on borate doping, attributed to a reduction in the hole (Mn 4+ ) concentration. In order to investigate the potential of these materials as SOFC cathodes, the chemical compatibility with Gd 0.1 Ce 0.9 O 1.95 (CGO10) has also been investigated. For the calcium manganites, the lowest temperature examined without reaction was 900 C, with minor amounts of Ca 4 Mn 3 O 10 observed at 1000 C. Composites of these cathode materials with 50% CGO10 were examined on dense CGO10 pellets and the area specific resistances (ASR) in symmetrical cells were determined. The ASR values, at 800 C, were 1.50, 0.37 and 0.30 U$cm 2 for CaMnO 3 , CaMn 0.95 B 0.05 O 3Àd and CaMn 0.95 P 0.05 O 3Àd , respectively. For the lanthanum strontium manganites, the B-doped compositions showed an improvement in the ASR values with respect to the parent compounds, despite the lower electronic conductivity. This may be due to an increase in ionic conductivity due to borate incorporation leading to the formation of oxide ion vacancies. Thus these preliminary results show that oxyanion doping has a beneficial effect on the performance of perovskite manganite cathode materials, and suggests that this doping strategy warrants further investigation in other perovskite cathode systems.

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“…Sr for La [1][2][3][4][5]. In this study we investigate an alternative strategy, the incorporation of oxyanions (borate and phosphate).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterisation of oxyanion-doped manganites for potential application as SOFC cathodes

et al. 2012

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“…Mixed conducting oxides have been attracting much attention in view of their promising applications, such as cathode and anode materials for solid oxide fuel cells [1], membranes for pure oxygen production and conversion of hydrocarbons to value-added products [2][3][4][5][6][7][8][9]. Over the past two decades, a number of mixed conducting materials based on perovskite-type oxides have been developed to meet many kinds of requirements in practical applications.…”

Section: Introductionmentioning

confidence: 99%

Design and experimental investigation of oxide ceramic dual-phase membranes

Zhu

Liu

et al. 2012

Journal of Membrane Science

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“…Solid Oxide Fuel Cells (SOFCs) are attracting considerable interest as next generation energy conversion devices due to their high efficiencies and accompanying low emissions. For the electrolyte in such devices, a material displaying either high oxide ion conductivity or proton conductivity at elevated temperatures is required, with the main focus of research in this field being materials with the fluorite or perovskite structures [1][2][3] . One of the most well known perovskite-related oxide ion conductors is Ba 2 In 2 O 5 , whose oxide ion conductivity is closely linked to its crystal structure 4,5 .…”

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confidence: 99%