Issue 10, 2019

Revisiting the charge compensation mechanisms in LiNi0.8Co0.2−yAlyO2 systems

Abstract

Oxygen participation, arising from increased transition metal–oxygen covalency during delithiation, is considered essential for the description of charge compensation in conventional layered oxides. The advent of high-resolution mapping of the O K-edge resonant inelastic X-ray scattering (RIXS) provides an opportunity to revisit the onset and extent of oxygen participation. Combining RIXS with an array of structural and electronic probes for the family of Ni-rich LiNi0.8Co0.2−yAlyO2 cathodes, we identify common charge compensation regimes that are assigned to formal transition metal redox (<4.25 V) and oxygen participation through covalency (>4.25 V). From O K-edge RIXS maps, we find the emergence of a sharp RIXS feature in these systems when approaching full delithiation, which has previously been associated with lattice oxidized oxygen in alkali-rich systems. The lack of transition metal redox signatures and strong covalency at these high degrees of delithiation suggest this RIXS feature is similarly attributed to lattice oxygen charge compensation as in the alkali-rich systems. The RIXS feature's evolution with state of charge in conventional layered oxides is evidence that this feature reflects the depopulation of occupied O 2p states associated with oxygen participation.

Graphical abstract: Revisiting the charge compensation mechanisms in LiNi0.8Co0.2−yAlyO2 systems

Supplementary files

Article information

Article type
Communication
Submitted
20 Mai 2019
Accepted
13 Jun 2019
First published
23 Jul 2019
This article is Open Access
Creative Commons BY-NC license

Mater. Horiz., 2019,6, 2112-2123

Revisiting the charge compensation mechanisms in LiNi0.8Co0.2−yAlyO2 systems

Z. W. Lebens-Higgins, N. V. Faenza, M. D. Radin, H. Liu, S. Sallis, J. Rana, J. Vinckeviciute, P. J. Reeves, M. J. Zuba, F. Badway, N. Pereira, K. W. Chapman, T. Lee, T. Wu, C. P. Grey, B. C. Melot, A. Van Der Ven, G. G. Amatucci, W. Yang and L. F. J. Piper, Mater. Horiz., 2019, 6, 2112 DOI: 10.1039/C9MH00765B

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