Electrode materials for lithium rechargeable batteries: Synthesis, spectroscopic studies and electrochemical performance.

Three distinct $\rm Li\sb{x}V\sb2O\sb5$ phases, $\delta, \ \varepsilon, $ and $\gamma$-$\rm Li\sb{x}V\sb2O\sb5, $ were obtained through a chemical intercalation reaction and solid state reactions. Infrared and Raman spectra were recorded for the three phases. The spectral changes were interpreted in terms of the local structural changes of the vanadium-oxygen polyhedra. Although the $\delta$ and $\varepsilon$ phases have very similar powder x-ray diffraction patterns, IR and Raman studies showed these two phases adopt distinctive local structural environments. These results demonstrate that IR and Raman spectroscopy are important techniques for the structural analysis of intercalation materials.For the first time novel mesostructural materials were synthesized as electrode materials for the lithium rechargeable battery. The well-ordered mesostructural materials provide an ideal host for lithium transport processes. The preliminary results on the manganese oxide-based cathode and tin oxide-based anode show that the templating synthesis technique may provide important electrode materials for battery applications.In situ Raman spectra of $\rm Li\sb{x}V\sb2O\sb5$ were successfully recorded on a operating lithium rechargeable battery. Distinctive spectral changes were observed at different lithium intercalation levels and interpreted in terms of the slight rearrangements of the V-O structural units. The results show that in situ Raman spectroscopy may become an important nondestructive technique in investigating the irreversible structural changes in electrode materials and evaluating battery performance.Single crystals of $\rm Li\sb{1.1}V\sb3O\sb8$ and $\rm\sp6Li\sb{1.1}V\sb3O\sb8$ were prepared using solid state synthesis techniques. IR spectra and polarized Raman spectra were recorded on the $\rm Li\sb{1.1}V\sb3O\sb8$ and $\rm\sp6Li\sb{1.1}V\sb3O\sb8$ crystals and a lithiated phase, $\rm Li\sb4V\sb3O\sb8.$ Factor group analysis method was used to interpret the spectral changes. These spectroscopic results provide insight into the structural modifications originating from lithium intercalation/deintercalation processes.The lithium rechargeable battery is the newest member of the rechargeable battery family and is best known for its high energy density, long battery life, low self-discharge rate and light weight. This battery may become one of the most important energy sources in consumer market, industrial and military applications. Intercalation compounds play a critical role in determining the overall performance of a lithium rechargeable battery. The common intercalation materials for battery applications are layered structure $\rm Li\sb{x}CoO\sb2, $ spinel $\rm Li\sb{x}Mn\sb2O\sb4$ and lithium vanadium oxides, $\rm Li\sb{x}V\sb2O\sb5$ and $\rm Li\sb{x}V\sb3O\sb8.