Performances and Ageing Mechanisms of LiMn1-XFexPO4 // Graphite Prototype Cells

Olivine C-LiFePO₄ has been intensively studied since 1997 ^[1] due to its high thermal stability and the expected material cost reduction compared to usual cobalt based oxides. However, the energy density loss induced by the low operating voltage of LiFePO₄, 3.45V, leads to consider LiMnPO₄, 4.0V, as a promising candidate. But without dopants this material is kinetically limited: iron substitution seems to be a solution to make its utilization possible.

Several publications^[2],[3],[4] present promising results on this type of material with good rate capabilities, good cycle life, but these results are mainly obtained in half cells vs Li° with low loaded electrodes.

Our work is focused on C-LiMn_2/3Fe_1/3PO₄which has shown an excellent cyclability in half cells vs Li°.

Prototype cells vs graphite have been assembled using high loaded electrodes, with a design close to industrial cells. Results obtained show:

- excellent rate capability: >90% of capacity is recovered at 5C

- excellent cycle life: 80% of capacity is still remaining after 900 cycles

 The study of ageing mechanisms by post-mortem analyses will be discussed.

Acknowledgment: All results presented here have been obtained on a material supplied by Clariant

[1] A. K. Padhi, K. S. Nanjundaswamy and J. B. Goodenough, Journal of The Electrochemical Society 1997, 144, 1188-1194.

[2] S.-M. Oh, H.-G. Jung, C. S. Yoon, S.-T. Myung, Z. Chen, K. Amine and Y.-K. Sun, Journal of Power Sources 2011, 196, 6924-6928.

[3] B. Z. Li, Y. Wang, L. Xue, X. P. Li and W. S. Li, Journal of Power Sources 2013.

[4] L. Hu, B. Qiu, Y. Xia, Z. Qin, L. Qin, X. Zhou and Z. Liu, Journal of Power Sources 2014, 248, 246-252.