Electronic limitations of lithium diffusibility. From layered and spinel toward novel olivine type cathode materials

The ability and efficiency of lithium intercalation into transition metal compounds have been found to depend strongly on their electronic structure. This work is a brief review of physicochemical properties of intercalated transition metal compounds with layered, spinel or olivine type structure in order to correlate their microscopic electronic properties, i.e. the nature of electronic states with the efficiency of lithium intercalation process that is controlled by the chemical diffusion coefficient of lithium. The data concerning cell voltages and character of discharge curves for various materials are correlated with the nature of chemical bonding and electronic structure following it. The nature of the metallic type conductivity of doped phospho-olivine is discussed and some fundamental arguments against the bulk nature of the observed high electronic conductivity are presented. (c) 2005 Elsevier B.V. All rights reserved.