Abstract
We have demonstrated that silicophosphate matrices with various P2O5 contents can be used to produce medium-temperature highly conductive CsH2PO4-based composites. The low-temperature conductivity of all the composites studied is higher than that of the salt at low humidity by up to three and half to four orders of magnitude. The phase transition disappears with increasing additive content. The proton conductivity, thermal characteristics, and phase composition of the salt are shown to depend significantly not only on the composition of the composite but also on that of the silicophosphate matrix. The composites with Si : P = 1 : 0.14 contain disordered CsH2PO4 in the range x = 0.1–0.6. Increasing the percentage of the heterogeneous component leads to CsH2PO4 amorphization at x = 0.7 and the formation of the CsH5(PO4)2 compound at x = 0.8–0.9. The thermodynamic properties and thermal stability of the composites vary in accordance with this. We have assessed the thermal stability of the electrolytes of various compositions under isothermal conditions at 200–210°C and water vapor content of ≃0.6–1% in air in prolonged tests. The thermal stability of the materials is shown to depend significantly on both the percentage of the salt in the composite and the composition of the matrix. We have determined the optimal thermal and transport characteristics of the composites based on silicophosphate gel with lower phosphorus content. This opens up the possibility of using them as membranes in medium-temperature hydrogen fuel cells.
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References
Uvarov, N.F., Kompozitsionnye tverdye elektrolity (Solid Composite Electrolytes), Sib. Otd. Ross. Akad. Nauk, 2008.
Yaroslavtsev, A.B., Composite ion conductors: from inorganic composites to hybrid membranes, Usp. Khim., 2009, vol. 78, no. 11, pp. 1094–1112.
Uvarov, N.F., Ponomareva, V.G., and Lavrova, G.V., Composite solid electrolytes, Russ. J. Electrochem., 2010, vol. 46, pp. 722–733.
Burgina, E.B., Ponomareva, V.G., Baltakhinov, V.P., and Kostrovskii, V.G., Spectroscopic study of the structure of and proton conduction mechanism in CsHSO4 and CsHSO4/SiO2 Composites, Zh. Strukt. Khim., 2005, vol. 46, no. 4, pp. 630–640.
Ponomareva, V. and Lavrova, G., Controlling the proton transport properties of solid acids via structural and microstructural modification, J. Solid State Electrochem., 2011, vol. 15, pp. 213–221.
Ponomareva, V.G. and Lavrova, G.V., Proton composite electrolytes based on solid acids, Fast Proton-Ion Transport Compounds, Mioč, U. and Davidovič, M., Eds., Trivandrum: Transworld Research Network, 2010, pp. 19–42.
Ponomareva, V.G., Medium-temperature proton-conducting inorganic membranes, Membrany i membrannye tekhnologii (Membranes and Membrane Technologies), Yaroslavtsev, A.B., Ed., Moscow: Nauchnyi Mir, 2013, pp. 169–218.
Ponomareva, V.G. and Shutova, E.S., High-temperature behavior of CsH2PO4 and CsH2PO4-SiO2 composites, J. Solid State Ionics, 2007, vol. 178, pp. 729–734.
Ponomareva, V.G. and Shutova, E.S., New mediumtemperature proton electrolytes based on CsH2PO4 and silicophosphate matrices, Inorg. Mater., 2014, vol. 50, no. 10, pp. 1050–1055.
Lavrova, G.V., Burgina, E.B., Matvienko, A.A., and Ponomareva, V.G., Bulk and surface properties of ionic salt CsH5(PO4)2, Solid State Ionics, 2006, vol. 177, pp. 1117–1122.
Clayden, N.J., Pernice, P., and Aronne, A., Multinuclear NMR study of phosphosilicate gels derived from POCl3 and Si(OC2H5)4, J. Non-Cryst. Solids, 2005, vol. 351, pp. 195–202.
Matsui, T., Muroyama, H., Kikuchi, R., and Eguchi, K., Development of novel proton conductors consisting of solid acid/pyrophosphate composite for intermediate-temperature fuel cells, J. Jpn. Petrol. Inst., 2010, vol. 53, pp. 1–11.
Matsuda, A., Kanzaki, T., Katan, Y., Tatsumisago, M., and Minami, T., Proton conductivity and structure of phosphosilicate gels derived from tetraethoxysilane and phosphoric acid or triethylphosphate, Solid State Ionics, 2001, vol. 139, pp. 113–119.
Tung, S.P. and Hwang, B.-J., High proton conductive glass electrolyte synthesized by an accelerated sol-gel process with water/vapor management, J. Membr. Sci., 2004, vol. 241, pp. 315–323.
Marchon, B. and Novak, A.,, Vibrational study of CsH2PO4 and CsD2PO4 single crystals, J. Chem. Phys., 1983, vol. 78, no. 5, pp. 2105–2119.
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Original Russian Text © V.G. Ponomareva, E.S. Shutova, 2014, published in Neorganicheskie Materialy, 2014, Vol. 50, No. 10, pp. 1141–1148.
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Ponomareva, V.G., Shutova, E.S. Electrical conductivity and structural properties of proton electrolytes based on CsH2PO4 and silicophosphate matrices with low phosphorus content. Inorg Mater 50, 1056–1062 (2014). https://doi.org/10.1134/S0020168514100136
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DOI: https://doi.org/10.1134/S0020168514100136