Effect of excess Li+in solution on LiFePO4preparation via wet chemical method

Article abstract of DOI:10.1016/j.jallcom.2016.07.029

Olivine structure LiFePO₄has attracted much attention as a promising cathode material for lithium ion batteries, and many approaches have been developed to produce electrochemically active LiFePO₄at low cost. Here lithium iron phosphate (LiFePO₄) was prepared via co-precipitation method by using FeSO₄·7H₂O, LiOH·H₂O, and o-H₃PO₄as the raw materials. The effects of Li:Fe:P molar ratios and solution pH value on the synthesis of LiFePO₄were studied. The results illustrated that besides of the pH value parameter which was reported in many other previous researches, excess Li⁺in the solution was another essential condition for pure LiFePO₄preparation. It suggested that excessive LiOH was not only a pH regulator, but also a precipitation promoter. Maintaining a certain excess Li⁺ion in solution was an efficient measure to avoid the formation of impurities.