Spinel oxide cathodes

Spinel LiMn204 has become an attractive cathode, as Mn is inexpensive and environmentally benign compared to Co and Ni involved in the layered oxide 

and Lii.i Mn1.gNio.1O3.gFo.2- 

Although the partial substitution of some of the ions by F ions is appeaHng 

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Veluchamy, A. Ikuta, H. and Wakihara. (2001). Boron Substituted Manganese Spinel Oxide Cathode For Lithium Ion Battery, Solid State Ionics, Vol. 142, p>p.l61-171 Wehr, MR. Richards, J.A. Adair, T.W. (1978). Physics of the Atom, Addison-Wessley, Reading, Mass. 

Mn,tCo3 t04) phase. This spinel oxide is broken up during reduction to make MnO t and a metallic surface. Due to the pre-existence of this Mn-M interaction, electronic promotion is much more easily achieved after reduction as well. It is worthwhile to mention that Mn,tCo3 t04 compounds are well studied in the literature, because they have important electrocatalytical properties. More specifically, spinel-type manganese oxides are widely used as precursors in the preparation of X-Mn02 ([ ]A[Mn2]B04], an oxide of technical interest due to its application as a cathode material for rechargeable cells. " ... 

Spinels provide another possibility for oxide cathodes [8]. Patents have been filed covering the thermally prepared spinels of Ni, Co, Fe and Mn [482]. However, very few details are available. Pure Co304 is easily reduced cathodically with dramatic changes of its properties [483]. Additives are necessary to slow down the cathodic reduction [8]. Studies in the field of catalysis can guide in the search for additives. Among others, La, Zr and A1 are expected to be the most efficient ones [484, 485]. No data are presently available to test this prediction. 

Formation mechanism of SEI layers on cathodes in Li-ion batteries, their thermal and electrochemical stabihty, and their roles in affecting the cycle life and safety characteristics are well documented by many researchers [43 6]. Here we present some recent data on identifying the surface layer generation and their composition on transition metal oxide cathodes like spinel and layered materials by various spectroscopic techniques. The structural changes and the reaction at the surface during the first delithiation process in Li-rich layered material are explained. The effects of additives and coatings on electrode materials to their electrochemical performance are also discussed at the end. 

James Hunter of Eveready Battery Co. was the first to patent spinel cathode material. The application of material to Li-ion system has been developed by J. M. Tarascon [59] and extensively studied by M. Thackeray [60]. Generally, lithium spinel oxides suitable for the cathode are limited to those with a normal spinel in which the lithium ions occupy the tetrahedral (8a) sites and the transition-metal ions reside at the octahedral (16d) sites. Currently, spinel is the center of much interest as the cathode material for large format lithium-ion cell for hybrid electric vehicle applications where high power, safety, and low cost are the strongly required features. 

Based on their structure, cathodes can be separated into three basic families layered oxides, spinels, and olivine phosphates. The three families differ greatly in their cell performance as well as in thermal properties. Layered oxide cathodes typically have higher specific capacities than spinels or phosphates. As a consequence of their structure, layered oxide materials are more energetic upon thermal runaway events due to the ease with which oxygen is liberated from their framework upon decomposition. 

This book offers various comprehensive ideas on anode and cathode nanomaterials for new-generation lithium-ion batteries. Silicon and tin nano-alloy systems as the anode, discussed in the first several chapters, and olivine and spinel oxides as the cathode, in the latter chapters, are presented as nano-electrode materials with high power and high energy capacity. Readers will get some important electrode concepts from this book. ... 

Choi S, Manthiram A (2002) Factors influencing the layered to spinel-like phase transition in layered oxide cathodes. J Electrochem Soc 149 A1157-A1163... 

Complex Base-Metal Oxides Complex oxide systems include the mixed oxides of some metals which have perovskite or spinel structure. Both the perovskites and the spinels exhibit catalytic activity toward cathodic oxygen reduction, but important differences exist in the behavior of these systems. 

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