| Olivine lithium iron phosphate LiFePO4（LFP） is one of the most promising cathodematerials for large-scale power systems owing to its low cost, environmental benignity,high theoretical capacity (170mAhg-1), moderate voltage （3.4V vs Li+/Li）, long cycle lifeand high safety. However, LFP suffers from poor ionic and electronic conductivity, whichbring difficulties for its application in high-rate lithium ion battery.LiFePO4（LFP） nanobars, microplates and nanorods have been selectivelysynthesized via a solvothermal method in a water-ethylene glycol （EG） binary solventwith H3PO4, LiOH·H2O, and FeSO4·7H2O as starting materials. The morphology and sizeof the as-obtained LFP products can be deliberately controlled by varying the volume ratioof EG to water. The formation mechanism and electrochemical properties of different LFPmorphologies have been investigated. With carbon coating, the Li-ion diffusioncoefficients of LFP nanorods, nanobars and micro-plates are2.58×10-9,2.91×10-10, and7.22×10-10cm2s-1, respectively. For the carbon-coated nanorods, excellent rate capabilityand cyclability were attained. At5C, the capacity was141mAh g-1for the first cycle andmaintains120mAh g-1after100cycles; at10C, the capacity was still as high as132mAhg-1.Nano-LiFe1/3Mn1/3Co1/3PO4/C solid solution was prepared via a solvothermalsynthesis method in a in a water-ethylene glycol （EG） binary solvent as cathode materialsfor lithium ion batteries. The particles is crystallized in an orthorhombic structure, andshow a platelike shap with a length of300-400nm, a breadth of100-150nm. Duringcharge-discharge cycles, LiFe1/3Mn1/3Co1/3PO4/C presented three plateaus correspondingto Fe3+/Fe2+, Mn3+/Mn2+, Co3+/Co2+redox couples, and show a discharge capacity of142.2mAh/g in the first cycle, remaining92.6mAh/g after50cyles at0.2C. |
