Merck
  • Home
  • Search Results
  • Calcium manganite as oxygen electrode materials for reversible solid oxide fuel cell.

Calcium manganite as oxygen electrode materials for reversible solid oxide fuel cell.

Faraday discussions (2015-07-28)
Chengsheng Ni, John T S Irvine
ABSTRACT

For an efficient high-temperature reversible solid oxide fuel cell (RSOFC), the oxygen electrode should be highly active for the conversion between oxygen anions and oxygen gas. CaMnO(3-δ) (CM) is a perovskite that can be readily reduced with the formation of Mn(3+) giving rise to oxygen defective phases. CM is examined here as the oxygen electrode for a RSOFC. CaMn(0.9)Nb(0.1)O(3-δ) (CMN) with Nb doping shows superior electric conductivity (125 S cm(-1) at 700 °C) compared with CM (1-5 S cm(-1) at 700 °C) in air which is also examined for comparison. X-ray diffraction (XRD) data show that CM and CMN are compatible with the widely used yttria-stabilized zirconia (YSZ) electrolyte up to 950 °C. Both materials show a thermal expansion coefficient (TEC) close to 10.8-10.9 ppm K(-1) in the temperature range between 100-750 °C, compatible with that of YSZ. Polarization curves and electrochemical impedance spectra for both fuel cell and steam electrolysis modes were investigated at 700 °C, showing that CM presented a polarization resistance of 0.059 Ω cm(2) under a cathodic bias of -0.4 V while CMN gave a polarization resistance of 0.081 Ω cm(2) under an anodic bias of 0.4 V. The phase stability up to 900 °C of these materials was investigated with thermogravimetric analysis (TGA) and variable temperature XRD.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Manganese(IV) oxide, ReagentPlus®, ≥99%
Sigma-Aldrich
Manganese(IV) oxide, activated, ~85%, <10 μm
Sigma-Aldrich
Manganese(IV) oxide, 10 μm, reagent grade, ≥90%
Sigma-Aldrich
Calcium carbonate, BioReagent, suitable for insect cell culture, ≥99.0%
Sigma-Aldrich
Calcium carbonate, BioXtra, ≥99.0%
Sigma-Aldrich
Calcium carbonate, puriss., meets analytical specification of Ph. Eur., BP, USP, FCC, E170, precipitated, 98.5-100.5% (based on anhydrous substance)
Sigma-Aldrich
Calcium carbonate, Vetec, reagent grade, 99%
Sigma-Aldrich
Calcium carbonate, anhydrous, free-flowing, Redi-Dri, ReagentPlus®, ≥99%
Sigma-Aldrich
Calcium carbonate, ReagentPlus®
Sigma-Aldrich
Calcium carbonate, ACS reagent, ≥99.0%, powder
Sigma-Aldrich
Calcium carbonate, ACS reagent, chelometric standard, 99.95-100.05% dry basis
Sigma-Aldrich
Calcium carbonate, powder, ≤50 μm particle size, 98%
Sigma-Aldrich
Calcium carbonate, ≥99.995% trace metals basis
Sigma-Aldrich
Calcium carbonate, BioUltra, precipitated, ≥99.0% (KT)
Sigma-Aldrich
Calcium carbonate, 99.999% trace metals basis