Visualization of O-O peroxo-like dimers in high-capacity layered oxides for Li-ion batteries

• Published in: Science (American Association for the Advancement of Science) Vol. 350; no. 6267; pp. 1516 - 1521
• Main Authors: McCalla, Eric, Abakumov, Artem M., Saubanère, Matthieu, Foix, Dominique, Berg, Erik J., Rousse, Gwenaelle, Doublet, Marie-Liesse, Gonbeau, Danielle, Novák, Petr, Van Tendeloo, Gustaaf, Dominko, Robert, Tarascon, Jean-Marie
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 18.12.2015; The American Association for the Advancement of Science; American Association for the Advancement of Science (AAAS); AAAS
• Subjects: Batteries; Bonding; Cathodes; Condensed Matter; Dimers; Electronics; Lithium; Materials Science; Neutron diffraction; Oxides; Physics; Rechargeable batteries; Redox reactions
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.aac8260

Lithium-ion (Li-ion) batteries that rely on cationic redox reactions are the primary energy source for portable electronics. One pathway toward greater energy density is through the use of Li-rich layered oxides. The capacity of this class of materials (>270 milliampere hours per gram) has been shown to be nested in anionic redox reactions, which are thought to form peroxo-like species. However, the oxygen-oxygen (O-O) bonding pattern has not been observed in previous studies, nor has there been a satisfactory explanation for the irreversible changes that occur during first delithiation. By using Li₂IrO₃ as a model compound, we visualize the O-O dimers via transmission electron microscopy and neutron diffraction. Our findings establish the fundamental relation between the anionic redox process and the evolution of the O-O bonding in layered oxides.