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Synthesis and characterization of cathode materials for lithium ion batteries


In modern society the need for portable power sources with lower dimensions has emerged, which resulted in rapid expansion of the lithium battery industry. Intensive world-wide efforts are taking place to push the technology even further to much more demanding applications such as large and fast batteries, capable of working at elevated temperatures for both electric and hybrid electric vehicles. Among the promising materials for positive electrodes of Li-ion rechargeable batteries, lithium iron phosphate LiFePO4 is the most attractive candidate. However, there are some limitations that occur while reaching theoretical performances. The major drawback of LiFePO4 is its low electronic conductivity, which may result in a loss of capacity during high-rate discharge, a major inconvenience in power-demanding applications. That is why a great deal of effort has been made to improve the electric conductivity. It has been demonstrated that this could be achieved by coating LiFePO4 particles with some conductive material; usually carbon is a material of choice. 

During past several years, in order to keep up with world-wide trends in the scientific society, the Institute has conducted several serious researches in the lithium-ion battery field, concerning both the synthesis and the characterization of various cathode materials for lithium-ion batteries. The main focus of the research are different intercalation compounds that have the possibility to intercalate and deintercalate lithium ion within the structure without significant volume change. Spinel-type lithium manganates and their metal-substituted forms have already been investigated. A new generation of cathode materials, i.e. olivine-type LiMPO4  (M = Fe, Mn, Ni, Co) with the highlight on lithium iron phosphate and its carbon composite were synthesized and studied, too. Further investigations will include not only lithium iron phosphates but several other materials such as silicates, sulphates, and titanates.


TEM image of LiFePO4/C composite obtained by sonochemical precipitation.
Arrows point out 2-3 nm thick layer of amorphous carbon




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