Journal of Power Sources 160 (2006) 789–795
Solubility and electrochemical studies of LiFeO
materials for the MCFC cathode application
, Athula Wijayasinghe
, Michel Cassir
, Bill Bergman
Laboratoire d’Electrochimie et de Chimie Analytique, UMR 7575 CNRS-ENSCP, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05, France
Department of Materials Science and Engineering, KTH, Royal Institute of Technology, Sweden
Department of Chemical Engineering and Technology, KTH, Royal Institute of Technology, Sweden
Institute of Fundamental Studies, Kandy, Sri Lanka
Available online 12 June 2006
The dissolution of the state-of-the-art lithiated NiO is still considered as one of the main obstacles to the commercialisation of the molten
carbonate fuel cell (MCFC). Development of alternative cathode materials has been considered as a main strategy for solving this problem. Ternary
compositions of LiFeO
and NiO are expected to decrease the cathode solubility while ensuring a good electrical conductivity and
electrochemical activity towards the oxygen reduction.
In this work, new material compositions in the LiFeO
–NiO ternary system were synthesised using Pechini method and investigating
their electrical conductivity by the DC four probe method. Then the inﬂuence of the cobalt content in the composition was determined in terms of
AC impedance analysis and solubility measurements after 200 h of immersion in Li
C. The DC electrical conductivity study
reveals the ability of improving the electrical conductivity, adequate for MCFC cathode application, by controlling the Co content of the composition.
A special attention was given to the evolution of the open circuit potential as a function of time and to the impedance spectroscopy characterization
related to microstructure modiﬁcations. Taking into account solubility, electrical conductivity, as well as electrochemical performance in the fuel
cell, this study reveals the possibility of using LiFeO
–NiO ternary materials for MCFC cathode.
© 2006 Elsevier B.V. All rights reserved.
Keywords: MCFC; Cathode; LiFeO
–NiO ternary materials; Open circuit potential; Solubility; Impedance spectroscopy
The dissolution of the state-of-the-art lithiated NiO cathode
material is considered as a major lifetime limiting factor and a
major obstacle for the development of the molten carbonate fuel
cell (MCFC) technology [1,2]. Modiﬁcation of the electrolyte
composition, by increasing its basicity, is considered as a solu-
tion to overcome this obstacle [3–5]; however, it may lead to a
performance decrease. Another solution is the modiﬁcation of
the state-of-the-art NiO cathode material. Some authors have
proposed the protection of this Ni-based cathode by a cobalt-
based oxide layer [6,7]. On the other hand, development of
alternative cathode materials is considered as a main strategy
to solve the cathode dissolution problem.
Corresponding author. Tel.: +33 1 55 42 12 35; fax: +33 1 44 27 67 50.
E-mail addresses: firstname.lastname@example.org (A. Ringued
email@example.com (M. Cassir).
In searching for new cathode materials, the emphasis should
be mainly given to the stability of the candidate materials under
MCFC working conditions. Moreover, the candidate material
should possess an adequate electrical conductivity and electro-
catalytic activity . LiFeO
, which were earlier
supposed to be the most promising candidates, have been exten-
sively studied; however, none of them could directly substitute
lithiated NiO. Though LiFeO
shows a negligible dissolution
rate, the cathodes showed very low performance due to intrinsic
materials’ properties, such as poor oxygen reduction kinetics
and electrical conductivity. On the other hand, porous LiCoO
cathodes show sufﬁcient electrical conductivity but their low
mechanical strength and high cost have limited their practi-
cal use in MCFC stacks. Moreover, considerably high contact
resistance of LiCoO
cathodes with the current collector have
obstructed the direct substitution of lithiated NiO by LiCoO
The possibility of improving these single candidates, dop-
ing or forming into mixed oxides, has also been investigated.
0378-7753/$ – see front matter © 2006 Elsevier B.V. All rights reserved.