The defect chemistry of LiFePO4 prepared by hydrothermal method at different pH values

✍ Scribed by Jiali Liu; Rongrong Jiang; Xiaoya Wang; Tao Huang; Aishui Yu

• Book ID: 104025696
• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 568 KB
• Volume: 194
• Category: Article
• ISSN: 0378-7753
• DOI: 10.1016/j.jpowsour.2009.05.007

✦ Synopsis

LiFePO 4 has attracted broad attention as a promising cathode material for lithium ion batteries. One of the key issues related to LiFePO 4 performance lies on the intrinsic characteristic of Li/Fe inter-site mixing. To explore the effect of the defect chemistry on electrochemical behavior, LiFePO 4 is synthesized by hydrothermal method with pH value varying from 11.04 to 5.40. The results show that pure phase of LiFePO 4 could only be obtained at slightly basic and neutral conditions, and Rietveld refinements reveal that the degree of vacancies and inter-site mixing increase with decreasing pH value. The amounts of Fe on Li sites is nearly zero at pH value of 8.19, whereas 3.5% at 6.30. EIS measurements confirm that the occupation of Fe on Li sites will block the one-dimensional tunnel for lithium ion diffusion. It is vital to prevent the defect chemistry of LiFePO 4 by optimizing the synthesis conditions.