Elucidating the diffusion pathway of protons in ammonium polyphosphate: A potential electrolyte for intermediate temperature fuel cells

Authors
Sun, Chunwen; Lopez, Carlos Alberto; Alonso, José Antonio
Publication Year
2017
Language
English
Format
article
Status
Published version
Description
Ammonium polyphosphate (NH4PO3) is a potential electrolyte material for intermediate temperature fuel cells (150-250 °C). The crystal structure of NH4PO3, including the H positions, is unravelled by neutron powder diffraction (NPD) data by successive Fourier synthesis from the polyphosphate backbone. The structure consists of zig-zag chains aligned along the [001] directions of tetrahedral phosphate PO4 units that are connected through O3 atoms with a P-O3-P angle of 126.3(5)°. The proton conductivity mechanism of NH4PO3 is clarified from the thermal evolution of the structure. It shows that some H atoms subtly shift at high temperatures, resulting in a weakening of certain H-bonds, thus increasing the lability of those H atoms involved in the proton conduction mechanism. Conductivity measurements in humid air and H2 of NH4PO3 show high proton conductivities of 1.2 × 10-5 to 2.61 × 10-3 S cm-1 and 2.2 × 10-5 to 2.69 × 10-3 S cm-1, respectively, in the temperature range of 50 °C to 275 °C.
Fil: Sun, Chunwen. Chinese Academy of Sciences; República de China
Fil: Lopez, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; Argentina
Fil: Alonso, José Antonio. Instituto de Ciencia de Materiales de Madrid; España
Subject
Ammonium polyphosphate
proton conductivity
neutron powder diffraction
intermediate temperature fuel cells
Otras Ciencias Químicas
Ciencias Químicas
CIENCIAS NATURALES Y EXACTAS
Access level
Open access
License
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repository
CONICET Digital (CONICET)
Institution
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identifier
oai:ri.conicet.gov.ar:11336/65091