Both LiCoO2 and LiNi1/3Mn1/3Co1/3O2 layered cathode materials are investigated in our studies. P3 phase of CoO2, the end member of the LixCoO2, is found in both chemically and electrochemically delithiated materials. Delithiated LixCoO2 specimens decompose into fine Co3O4 and LiCoO2 particles starting at around 200 °C. This decomposing reaction is proved by in-situ X-ray diffraction and in-situ transmission electron microscopy investigations. The structures of pristine and cycled LiNi1/3Mn1/3Co1/3O2 are investigated by electron diffraction. Single and polycrystalline crystals are found in this material. The partial substitution of Co by Ni and Mn in LiNi1/3Mn1/3Co1/3O2 opens up the possibility of different cation configurations in the crystal lattice. Both 3Rm symmetry and superlattices are identified in this material. The number of particles with superlattices in pristine material (40%) is much bigger than cycled material at discharge state (10%).

The rechargeable secondary Lithium ion (Li-ion) battery is expected to grow to more than $6.3 billion by 2012 from ~$4.6 billion in 2006. With the development of personnel electronics, hybrid and electric vehicles, Li-ion batteries will be more in demand. However, Li-ion batteries are not widely recycled because it is not economically justifiable (in contrast, at present more than 97% Lead-acid batteries are recycled). So far, no commercial methods are available to recycle different chemical Li-ion batteries economically and efficiently. Considering our limited resources, environmental impact, and national security, Li-ion batteries must be recycled. A new methodology with low temperature and high efficiency is proposed in order to recycle Li-ion batteries economically and with industrial viability. The separation and synthesis of cathode materials (most valuable in Li-ion batteries) from recycled components are the main focus of the proposed research. The analytical results showed that the recycling process is practical and has high recovery efficiency, create great commercial value as well.

A Comprehensive review of literature on electrode materials for lithium-ion batteries is provided in Chapter 1 of the thesis. Chapter 2 deals with the studies on porous, sub-micrometer size LiNi1/3Co1/3O2 as a positive electrode material for Li-ion cells synthesized by inverse microemulsion route and polymer template route. The electromechanical characterization studies show that carbon-coated LiNi1/3Co1/3O2 samples exhibit improved rate capability and cycling performance. Furthermore, it is anticipated that porous LiNi1/3Co1/3O2 could be useful for high rates of charge-discharge cycling. Synthesis of sub-micrometer size, porous particles of LiNi1/3Co1/3O2 using a tri-block copolymer as a soft template is carried out. LiNi1/3Co1/3O2 sample prepared at 900ºC exhibits a high rate capability and stable capacity retention of cycling. The electrochemical performance of LiNi1/3Co1/3O2 prepared in the absence of the polymer template is inferior to that of the sample prepared in the presence of the polymer template. Chapter 4 involves the synthesis of sub-micrometer size particles of LiMn2O4 in quaternary microemulsion medium. The electrochemical characterization studies provide discharge capacity values of about 100 mAh g-1 at C/5 rate and there is moderate decrease in capacity by increasing the rate of charge-discharge cycling. Studies also include charge-discharge cycling as well as ac impedance studies in temperature range from -10 to 40º C. Chapter 5 reports the synthesis of nano-plate LiFePO4 by polyol route starting from two reactants, namely, FePO42H2O and LiOH.2H2O. The electrodes fabricated out of nano-plate of LiFePO4 exhibit a high electrochemical activity. A stable capacity of about 155 mAh g-1 is measured at 0.2 C over 50 charge-discharge cycles. Mesoporous LiFePO4/C composite with two sizes of pores is prepared for the first time via solution-based polymer template technique. The precursor of LiFePO4/C composite is heated at different temperatures in the range from 600 to 800ºC to study the effect of crystalllinity, porosity and morphology on the electrochemical performance. The compound obtained at 700ºC exhibits a high rate capability and stable capacity retention on cycling with pore size distribution around 4 and 46nm. In Chapter 6, the electrochemical characterization of LiMn2O4 in an aqueous solution of 5 M LiNO3 is reported. A typical cell employing LiMn2O4 as the positive electrode and V2O5 as the negative electrode was assembled and the characterized by charge-discharge cycling in 5 M LiNO3 aqueous electrolyte. Furthermore, it is shown that Li+-ion in LiMn2O4 can be replaced by other divalent ions resulting in the formation of MMn2O4 (M = Ca, Mg, Ba and Sr) in aqueous M(NO3)2 electrolytes by subjecting LiMn2O4 electrodes to cyclic voltametry. Cyclic voltammetry and chronopotentiometry studies suggest that MMn2O4 can undergo reversible redox reaction by intercalation/deintercalation of M2+-ions in aqueous M(NO3)2 electrolytes.

The aim of this work is to describe the influence of temperature on the structure and chemical composition of electrode materials for Li-ion accumulators. Theoretical part of this thesis contains described terminology and general issues of batteries and their division. Every kind of battery is provided with a closer description of a specific battery type. A separate chapter is dedicated to lithium cells, mainly Li-ion batteries. Considering various composition of Li-ion batteries, the next subchapters deeply analyzes the most used cathode (with an emphasis on the LiFePO4, LiMn1/3Ni1/3Co1/3O2) and anode materials (with an emphasis on the Li4Ti5O12). The next chapters describe the used analytical methods: electron microscopy, energy dispersion spectroscopy and thermomechanical analysis. The practical part is devoted to the description of the individual experiments and the achieved results.