Investigations of cathode materials for lithium-ion batteries: Emphasis on synthesis and characterization of chromium oxides-based compounds

High performance cathode materials for lithium-ion or secondary lithium batteries were synthesized by solid state reactions. These materials possess high capacity, fast lithiumion diffusion and extended cycle life. The method involves modification of the composition and structure of the spinel lithium manganese oxide by doping with a small amount of chromium with CrO_2.65 as one of the starting materials to form a chromium-doped quaternary spinel phase in order to improve the stability of the spinel and the lithium-ion diffusion in the compound. Another approach deals with incorporation of cobalt or vanadium into the structure of chromium oxides to improve the stability and high-rate capability of these intercalation materials.; A mathematical model was developed for the lithium intercalation of a single spinel particle as a microelectrode under the stimulus of a cyclic linear potential sweep. The model includes both lithium diffusion within the particle and kinetics at the particle/electrolyte interface. The model is used to predict that peak currents depend linearly on the scan rate to a certain power with a constant term.