Silicates and titanates as high-energy cathode materials for Li-ion batteries

Several different cathode materials for Li-ion batteries with a general formula Li2MXO4 (M=Fe, Mn, Ni, V and X=Si, Ti) were synthesized and characterized. Generally those materials can be classified into the group of silicates with tetrahedral coordinated cations and into titanates with a rock-salt structure. The common characteristic of these two families of new cathode materials is two lithium cations in the structure and at lest theoretical possibility to exchange more than one electron per transition metal and consequently enable much higher specific capacity of battery. Detailed structural and electrochemical characterization (including some in-situ characterization techniques, like X-ray absorption and Mossbauer spectroscopy) are discussed in this paper. Influence of the structural stability and particle size is discussed based on the obtained electrochemical results. Finally we show for the first time operation of Li2FeSiO4 with graphite electrode at 60 degrees C.