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A Joint Computational and Experimental Evaluation of CaMn2O4 Polymorphs as Cathode Materials for Ca Ion Batteries
journal contribution
posted on 2016-09-14, 00:00 authored by M. Elena Arroyo-de Dompablo, Christopher Krich, Jessica Nava-Avendaño, Neven Biškup, M. Rosa Palacín, Fanny BardéThe
identification of potential cathode materials is a must for
the development of a new calcium-ion based battery technology. In
this work, we have first explored the electrochemical behavior of
marokite–CaMn2O4 but the experimental
attempts to deinsert Ca ion from this compound failed. First-principles
calculations indicate that in terms of voltage and capacity, marokite–CaMn2O4 could sustain reversible Ca deinsertion reactions;
half decalciation is predicted at an average voltage of 3.7 V with
a volume variation of 6%. However, the calculated barriers for Ca
diffusion are too high (1 eV), in agreement with the observed difficulty
to deinsert Ca ion from the marokite structure. We have extended the
computational investigation to two other CaMn2O4 polymorphs, the spinel and the CaFe2O4 structural
types. Full Ca extraction from these CaMn2O4 polymorphs is predicted at an average voltage of 3.1 V, but with
a large volume variation of around 20%. Structural factors limiting
Ca diffusion in the three polymorphs are discussed and confronted
with a previous computational investigation of the virtual-spinel
[Ca]T[Mn2]OO4. Regardless
the potential interest of [Ca]T[Mn2]OO4 as cathode for Ca ion batteries, calculations suggests
that the synthesis of this compound would hardly be feasible. The
present results unravel the bottlenecks associated with the design
of feasible intercalation Ca electrode materials, and allow proposing
guidelines for future research.