Solvothermal synthesis of lithium iron phosphate from a high concentration precursor

摘要

LiFePO4 cathode material was synthesized using a solvothermal method at various relatively high concentration precursors. The samples were prepared using LiOH·H2O, FeSO4·7H2O, H3PO4, and citric acid which are dissolved in ethylene glycol and water mixture solvent with various concentration of LiOH from 0.3 to 1.8 M while the Li:Fe:P molar ratio was fixed at 3:1:1. The precursors were heated in an autoclave at fixed temperature of 180°C for 8 hours. The prepared samples were characterized using an X-Ray Diffraction and Scanning Electron Microscopy to study the crystal structures and morphology of the prepared particles, respectively. It was found that LiFePO4 structures were observed at all various concentrations. However, a small part of crystal structure impurity was detected for the samples that fabricated at concentration 0.3 M and some coagulated part of sample from 1.5 M and 1.8 M. We found that the optimum precursor concentration for the present method and preparation condition was at 1.2 M of LiOH precursor.