Temperature-driven structural evolution of carbon modified LiFePO 4 in air

• Published in: RSC advances Vol. 5; no. 39; pp. 30537 - 30541
• Main Authors: Ni, Jiangfeng, Wang, Yue
• Format: Journal Article
• Language: English
• Published: 2015
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/C5RA04744G

Lithium iron phosphate (LiFePO 4 ) is an appealing cathode material for lithium ion batteries. However, the degradation of LiFePO 4 in air presents an unavoidable challenge, due to the vulnerability of divalent Fe against oxygen attack. In this work, we have carried out comprehensive research on the thermal stability and temperature-driven evolution of nanocarbon modified LiFePO 4 in air. The results show that LiFePO 4 retains structural stability up to 250 °C for short periods of exposure to air. At long exposure times, structural evolution occurs at a much lower temperature, 150 °C. The structural evolution proceeds as the temperature increases, and finishes at 400 °C. The final products are monoclinic Li 3 Fe 2 (PO 4 ) 3 and α-Fe 2 O 3 . A quantitative evolution map has been developed through electrochemical cyclic voltammetry and galvanostatic tests. The results show that the largest changes take place between 200 and 250 °C.