Fe Incorporated Near-Amorphous Mn Oxide for Mg Rechargeable Batteries

The researches toward more efficient, cost-effective and environmentally benign energy materials have been accelerated with successful utilization of Li ion battery technology to consumer electronics. Mg has been suggested as one of strong candidates due to several reasons. It is more abundant on Earth and safer than Li since it does not form the dendrites. Since the reversible behavior of Mg in the Grignard agents was revealed by Aurbach et. al..¹ Many research groups have reported studies with various cathode materials with specific crystal structure such as Chevrel structure.^2,3

In this study, Fe incorporated Mn oxide was synthesized via simple cost-effective co-precipitation method. Unlike the preceded studies, crystalline nature of the obtained material was near-amorphous. As given in Figure 1(a), every sample synthesized via co-precipitation method exhibited an amorphous nature. For optimization of electrochemical performance, Fe addition amount was controlled from 0.1 M to 0.3 M. Each sample was galvanostatically cycled from 1 V to 4 V vs. Mg in 0.5 M Mg(ClO₄)₂in propylene carbonate.

Figure 1(b) shows the voltage profile at 1^st cycle of no Fe contained, 0.1 M, 0.2 M and 0.3 M added sample. The capacity of 0.3 M added Fe (Best result) increased 33% with 91% coulombic efficiency compared to no Fe added oxide. Also, the charging potential showed a difference of 0.23V between no Fe added and 0.3 M Fe added sample. It is attributed to the pillar effect⁴ which supports the oxide structure during cycling.

References

1. D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H.

Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich

and E. Levi, Nature 407, 724-727 (2000)

2. E. Levi, G. Gershinsky, D. Aurbach, O. Isnard and G. Ceder, Chem. Mater. 21, 1390-1399 (2009)

3. Eli Lancry, E. Levi, Y. Gofer, M. D. Levi, D. Aurbach, J. Solid State Electrochem. 9, 259-266 (2005)

4. H. Liu, Q. Cao, L. J. Fu, C. Li, Y. P. Wu, H. Q. Wu, Electrochem. Comm. 8, 1553-1557 (2006)