Layered lithium transition metal oxide cathodes towards high energy lithium-ion batteries

Abstract

Development and discovery of cathode materials with superior performance seem to be tremendous challenges for Li-ion battery scientists. Since the topotactic reaction was first demonstrated in the 1970s, layered Li transition metal oxides (LiMO₂, M = Co, Ni, Mn) have been a shining star throughout the research and innovation in intercalation materials due to their appealing merits. Generally the basic LiMO₂ with a single kind of transition metal ion suffers from safety concerns and structural instability and can not support high energy Li-ion batteries. Nowadays, Li-stoichiometric mixed metal oxides and Li-excess Mn-based oxides have been considered as the most promising families of cathode materials for large-scale Li-ion batteries with high energy density used for transportation. In the present paper, with the help of a phase diagram tetrahedron, we provide an overview of the major developments in the field of LiMO₂ cathode materials. The changes in structure during Li extraction and the phase compatibility of Li mixed metal oxides are highlighted. The latest progress in the research of Li-excess Mn-based oxides is also included.