D. L. Proffit (Argonne National Laboratory), C. Kim (Lawrence Berkeley National Laboratory), P. Senguttuvan (Argonne National Laboratory), V. Duffort, L. F. Nazar (University of Waterloo), J. Cabana (JCESR at University of Illinois at Chicago), A. K. Burrell (JCESR at Argonne National Laboratory), J. T. Vaughey, and B. Key (Argonne National Laboratory)
Multivalent-ion chemistries such as Mg-ion are emerging as alternative battery systems to Li-ion. Current Mg-ion chemistries are limited to relatively low voltages and relatively low reversible specific capacities (1-2). Recent research on potential high voltage Mg-ion cathode materials and alternative anode materials such as transition metal oxides and metal alloys have highlighted the urgent need to understand structure activity relationships and insertion/intercalation phenomenon for development of such systems (3). Solid state NMR is a powerful tool to investigate local structure and insertion/intercalation phenomena, particularly for batteries as shown for Li-ion chemistries with
6Li and
7Li NMR (4, 5). However, the low natural abundance (10%) of the NMR active Mg isotope (
25Mg), highly quadrupolar nuclear spin of
25Mg (spin
5/
2) and very low gyromagnetic ratio (
i.e 30.6 MHz Larmor frequency relative to
1H = 500 MHz) limits the effective use of
25Mg NMR for solid Mg-ion battery materials (6). In this work, despite the challenges of
25Mg NMR, our recent efforts to characterize Mg environments in cathode materials such as MgMn
2O
4 spinels, MgV
2O
5, in anode materials such as h-TiO
2 and Mg-Sn alloys will be presented. Chemical magnesiation using dibutylmagnesium and preliminary electrochemical (de)mangesiation and the structral changes induced will be discussed. The results will summarize the effectiveness of the method in distinguishing side reactions or undesirable conversion reactions, including amorphous phases, from intercalation phenomenon.
References:
1. D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich, and E. Levi, Nature, 407 (6805), 724-727 (2000).
2. H. D. Yoo, I. Shterenberg, Y. Gofer, G. Gershinsky, N. Pour, and D. Aurbach, Energ Environ Sci, 6 (8), 2265-2279 (2013).
3. Magnesium Batteries 1 and 2, 224th Electrochemical Society Meeting, San Francisco CA, 2013
4. C. P. Grey and N. Dupre, Chem. Rev. (Washington, DC, U. S.), 104, 4493 (2004).
5. B. Key, R. Bhattacharyya, M. Morcrette, V. Seznec, J. M. Tarascon and C. P. Grey, Journal of the American Chemical Society, 131, 9239 (2009).
6. R. Dupree and M. E. Smith, Journal of the Chemical Society-Chemical Communications, 1483 (1988).
