Study of the morphology control and solid solution behaviour of Olivine LiMPO4 (M = Fe, Mn, and Co)

Lihium ion battery;LiMPO4;nanoparticle;hydrothermal synthesis;polyol process;solid solution;Chemistry

Kan, Wang Hay

University of Waterloo

关键词: Lihium ion battery;    LiMPO4;    nanoparticle;    hydrothermal synthesis;    polyol process;    solid solution;    Chemistry;   

Others  :  https://uwspace.uwaterloo.ca/bitstream/10012/4313/1/Thesis_April15_2009.pdf

瑞士|英语

来源: UWSPACE Waterloo Institutional Repository

【 摘 要 】

Lithium iron phosphate (LiFePO4) is one of the most promising cathode materials for lithiumion rechargeable batteries. It has a high theoretical specific capacity (170 mAh/g) andoperating potential (3.45 V vs. Li+/Li). Additionally, the material is extremely stable thermallyand electrochemically at ambient conditions, which is very suitable to be used in electricvehicles. However, the electronic and ionic conductivities of the material are quite low, whichlimits the power performance of the batteries. In the last decade, extensive work was reportedon various methods to improve the electronic conductivity extrinsically, for example carboncoating, metallic additives and molecular wiring. Nevertheless, energy density of the cells willbe reduced because of non-electrochemically active nature of the additives. In principle,electronic and ionic conductivities can be boosted intrinsically. One of the methods is toincrease the number of charge carriers in the material, for instance in two-phasesolid solution system LiαFePO4/Li1-βFePO4 or single solid solution phase LixFePO4. Since theformation of solid solution has been reported to be size dependent, it is highly desired to knowhow to synthesize LiFePO4 particles with different sizes. In this study, we have usedhydrothermal synthesis and polyol process to control the size of LiMPO4 (M: Fe, Mn, and Co)particles. We will present how we prepare particles with different sizes. Moreover, the solidsolution properties of various sizes of LiMPO4 (M: Mn and Fe) were studied. The result will bepresented.Part of the preliminary findings have been published in the peer-reviewed journals orconference presentations: 1) Journal of Materials Chemistry [Ellis B.; Kan W. H.; MakahnoukW. R. M.; Nazar L. F. J. Mater. Chem. 2007, 17 (30) 3248., 2) Journal of the AmericanivChemical Society [Lee K. T.; Kan W. H.; Nazar L. F. J. Am. Chem. Soc. (submitted)], 3)Material Research Society Meeting [Kan W. H.; Maunders C.; Badi S.; Ellis B.; Botton G.;Nazar L. F. MRS Fall Meeting 2008 in Boston]