Synthesis and characterization of metal doped derivatives and carbon coated olivine LiCoPO4

Abstract

Lithium batteries have almost entirely replaced their bulkier and less energetic counterparts such as nickel-cadmium and nickel-metal hydride batteries; especially in portable electronic devices and they dominate the field of advanced power sources at present. The major focus of contemporary studies on lithium ion batteries is two folds, one is improving the electrochemical performance of electrode materials and other is lowering the cost. This thesis deals with the preparation and characterization of LiCo1-xMxPO4 (M=Al, Mg, AlandMg) by citric acid assisted sol-gel method. It presents the development of CA-ISOL sol-gel method for production of nano-sized LiCoPO4 and carbon coated LiCoPO4 in a one-step heating process. Obviously, the routine approach to prepare electrode materials, which consists in mixing the electrode with carbon additives, was no longer sufficient, hence the need to pursue new concepts to enhance electron and ion transport in the electrode in order to overcome the above limitation. The following various materials processing approaches were tried by playing either with the intrinsic properties of the material (e.g. chemical composition); the morphology and texture of the particle (low temperature synthesis routes to obtain tailored particles); the material defects density, or the particles surfaces through either chemical means (carbon coating or physical means mechanical mixing with carbons) Among all of the above approaches, the ones dealing directly or indirectly with the metallic coating have been the most successful in fighting electronic ionic limitations since LiCoPO4/C electrode materials exhibited excellent improvement in Li-ion diffusion with sharp redox peaks. Commonly, such a positive effect is explained as due to the combined effects of carbon coating on nano LiMPO4 (M = Fe, Co, Mn) particles. These results can be used in the future to better characterize nanoparticles as active material for electrochemical characterization in Li-ion batteries. newline