Issue 11, 2019

Overall structural modification of a layered Ni-rich cathode for enhanced cycling stability and rate capability at high voltage

Abstract

The vital challenge in relation to layered Ni-rich cathodes is their pronounced structural degradation originating from cation mixing at high voltage, which causes serious electrode polarization and electrochemical deterioration. Herein, an overall structural modification strategy, which integrates a Li2GeO3 coating with gradient Ge-doping, was developed to improve the structural stability and create ordered diffusion channels in a layered Ni-rich cathode via interfacial fusion at high temperature. This effective strategy significantly enhances the reversible capacity retention, voltage stability and rate capability of the layered Ni-rich cathode at high voltage. We find that the Li2GeO3 coating inhibits interfacial side reactions to enhance the surface structural stability of the cathode materials. More importantly, the gradient Ge-doping plays a critical role in suppressing cation mixing to improve the ordered channels available for Li+ ion transport. The experimental observations, corroborated by first principle calculations, further reveal that Ge-doping not only alleviates structural degradation by increasing the phase transition energy barrier for layers to form spinel-like or rock-salt phases, but also facilitates fast Li+ diffusion kinetics via reducing the diffusion barrier. Our work provides a design idea for stabilizing the surface/bulk structure of advanced cathodes for high-performance Li-ion batteries.

Graphical abstract: Overall structural modification of a layered Ni-rich cathode for enhanced cycling stability and rate capability at high voltage

Supplementary files

Article information

Article type
Paper
Submitted
28 Dec 2018
Accepted
13 Feb 2019
First published
14 Feb 2019

J. Mater. Chem. A, 2019,7, 6080-6089

Overall structural modification of a layered Ni-rich cathode for enhanced cycling stability and rate capability at high voltage

M. Tang, J. Yang, N. Chen, S. Zhu, X. Wang, T. Wang, C. Zhang and Y. Xia, J. Mater. Chem. A, 2019, 7, 6080 DOI: 10.1039/C8TA12494A

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