Lithium manganese spinel materials for high-rate electrochemical applications

In order to successively compete with supercapacitors, an ability of fast discharge is a must for lithium-ion batteries. From this point of view, stoichiometric and substituted lithium manganese spinels as cathode materials are one of the most prospective candidates, especially in their nanosized form. In this article, an overview of the most recent data regarding physico-chemical and electrochemical properties of lithium manganese spinels, especially, LiMn2O4 and LiNi0.5Mn1.5O4, synthesized by means of various methods is presented, with special emphasis of their use in high-rate electrochemical applications. In particular, specific capacities and rate capabilities of spinel materials are analyzed. It is suggested that reduced specific capacity is determined primarily by the aggregation of material particles, whereas good high-rate capability is governed not only by the size of crystallites but also by the perfectness of crystals. The most technologically advantageous solutions are described, existing gaps in the knowledge of spinel materials are outlined, and the ways of their filling are suggested, in a hope to be helpful in keeping lithium batteries afloat in the struggle for a worthy place among electrochemical energy systems of the 21st century.