Cation-Disordered Lithium Transition Metal Oxides for Rechargeable Lithium Batteries

Layered lithium transition metal oxides, such as LiCoO₂, have been one of the most important classes of cathode materials for rechargeable lithium batteries [1,2]. In these materials, lithium and transition metal ions are well-segregated to form distinct layers which alternate in their crystal structure [1,2]. In general, well-layeredness in their structure has been considered necessary for high lithium mobility in the materials, and cation mixing has been observed to result in poor cyclability by slowing down lithium diffusion [3,4]. Such understanding and observations may have led researchers to disregard cation-disordered lithium transition metal oxides as promising cathode materials.

            Recently, we have identified a material (Li_1.211Mo_0.467Cr_0.3O₂) whose behavior questions our understanding of the effect of disorder on lithium transport [5]. This material forms as a layered rocksalt, but transforms to a disordered rocksalt after just a few charge-discharge cycles. Nevertheless, it cycles very well, exhibiting a specific capacity well above 250 mAh/g, which is rarely achieved even in well-layered materials. Using ab initio computations and Monte-Carlo simulations, we explain the performance of Li_1.211Mo_0.467Cr_0.3O₂, and propose a design paradigm for cation-disordered oxides as cathode materials [5].

[1] M. S. Whittingham, Chem. Rev. 104, 4271-4302 (2004).

[2] J. B. Goodenough, Y. Kim, Chem. Mater. 22, 587-603 (2010).

[3] K. Kang, Y. S. Meng, J. Bréger, C. P. Grey, G. Ceder, Science 311, 977-980 (2006).

[4] A. Rougier, P. Gravereau, C. Delmas, J. Electrochem. Soc. 143, 1168-1175 (1996).

[5] J. Lee, A. Urban, X. Li, D. Su, G. Hautier, G. Ceder, Science, 9 January 2014 (10.1126/science.1246432).