A 3.6 V lithium-based fluorosulphate insertion positive electrode for lithium-ion batteries

• Published in: Nature materials Vol. 9; no. 1; pp. 68 - 74
• Main Authors: Walker, W, Tarascon, J-M, Recham, N, Chotard, J-N, Dupont, L, Delacourt, C, Armand, M
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 01.01.2010
• Subjects: Batteries; Electrodes; Electronics; Innovations; Materials science
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/nmat2590

Li-ion batteries have contributed to the commercial success of portable electronics, and are now in a position to influence higher-volume applications such as plug-in hybrid electric vehicles. Most commercial Li-ion batteries use positive electrodes based on lithium cobalt oxides. Despite showing a lower voltage than cobalt-based systems (3.45 V versus 4 V) and a lower energy density, LiFePO(4) has emerged as a promising contender owing to the cost sensitivity of higher-volume markets. LiFePO(4) also shows intrinsically low ionic and electronic transport, necessitating nanosizing and/or carbon coating. Clearly, there is a need for inexpensive materials with higher energy densities. Although this could in principle be achieved by introducing fluorine and by replacing phosphate groups with more electron-withdrawing sulphate groups, this avenue has remained unexplored. Herein, we synthesize and show promising electrode performance for LiFeSO(4)F. This material shows a slightly higher voltage (3.6 V versus Li) than LiFePO(4) and suppresses the need for nanosizing or carbon coating while sharing the same cost advantage. This work not only provides a positive-electrode contender to rival LiFePO(4), but also suggests that broad classes of fluoro-oxyanion materials could be discovered.