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Anion Redox Chemistry in the Cobalt Free 3d Transition Metal Oxide Intercalation Electrode Li[Li 0.2 Ni 0.2 Mn 0.6 ]O 2

DOI: 10.1021/jacs.6b05111 DOI Help

Authors: Kun Luo (University of Oxford) , Matthew R. Roberts (University of Oxford) , Niccol├│ Guerrini (University of Oxford) , Nuria Tapia-ruiz (University of Oxford) , Rong Hao (University of Oxford) , Felix Massel (Department of Physics and Astronomy, Division of Molecular and Condensed Matter Physics, Uppsala University) , David M. Pickup (University of Kent) , Silvia Ramos (Diamond Light Source) , Yi-sheng Liu (Advanced Light Source, Lawrence Berkeley National Laboratory) , Jinghua Guo (Advanced Light Source, Lawrence Berkeley National Laboratory) , Alan V. Chadwick (University of Kent) , Laurent C. Duda (Department of Physics and Astronomy, Division of Molecular and Condensed Matter Physics, Uppsala University) , Peter Bruce (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of The American Chemical Society , VOL 138 , PAGES 11211 - 11218

State: Published (Approved)
Published: September 2016
Diamond Proposal Number(s): 14239

Abstract: Conventional intercalation cathodes for lithium batteries store charge in redox reactions associated with the transition metal cations, e.g., Mn3+/4+ in LiMn2O4, and this limits the energy storage of Li-ion batteries. Compounds such as Li[Li0.2Ni0.2Mn0.6]O-2 exhibit a capacity to store charge in excess of the transition metal redox reactions. The additional capacity occurs at and above 4.5 V versus Li+/Li. The capacity at 4.5 V is dominated by oxidation of the O-2(-) anions accounting for similar to 0.43 e(-)/formula unit, with an additional 0.06 e(-)/formula unit being associated with O loss from the lattice. In contrast, the capacity above 4.5 V is mainly O loss, similar to 0.08 e(-)/formula. The O redox reaction involves the formation of localized hole states on O during charge, which are located on O coordinated by (Mn4+/Li+). The results have been obtained by combining operando electrochemical mass spec on 180 labeled Li[Li0.2Ni0.2Mn0.6]O-2 with XANES, soft X-ray spectroscopy, resonant inelastic X-ray spectroscopy, and Raman spectroscopy. Finally the general features of O redox are described with discussion about the role of comparatively ionic (less covalent) 3d metal oxygen interaction on anion redox in lithium rich cathode materials.


Subject Areas: Materials, Chemistry, Energy

Instruments: B18-Core EXAFS

Other Facilities: Advanced Light Source, Lawrence Berkeley National Laboratory