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In situ Lithiated ALD Niobium Oxide for Improved Long Term Cycling of Layered Oxide Cathodes: A Thin-Film Model Study

preprint
revised on 26.03.2021, 10:29 and posted on 26.03.2021, 12:46 by Abdessalem Aribia, Jordi Sastre, Xubin Chen, Evgeniia Gilshtein, Ayodhya N. Tiwari, Yaroslav E. Romanyuk

Protective coatings applied to cathodes help to overcome interface stability issues and extend the cycle life of Li-ion batteries. However, within 3D cathode composites it is difficult to isolate the effect of the coating because of the additives and non-ideal interfaces. In this study we investigate niobium oxide (NbOx) as cathode coating in a thin-film model system, which provides simple access to the cathode-coating-electrolyte interface. The conformal NbOx coating was applied by atomic layer deposition (ALD) onto thin-film LiCoO2 cathodes. The cathode/coating stacks were annealed to lithiate the NbOx and ensure sufficient ionic conductivity. A range of different coating thicknesses were investigated to improve the electrochemical cycling with respect to the uncoated cathode. At a NbOx thickness of 30 nm, the cells retained 80% of the initial capacity after 493 cycles at 10 C, more than doubling the cycle life of the uncoated cathode film. At the same thickness, the coating also showed a positive impact on the rate performance of the cathode: 47% of the initial capacity was accessible even at ultrahigh charge-discharge rates of 100 C. Using impedance spectroscopy measurements, we found that the enhanced performance is due to suppressed interfacial resistance growth during cycling. Elemental analysis using TOF-SIMS and XPS further revealed a bulk and surface contribution of the NbOx coating. These results show that in situ lithiated ALD NbOx can significantly improve the performance of layered oxide cathodes by enhancing interfacial charge transfer and inhibiting surface degradation of the cathode, resulting in better rate performance and cycle life.

Funding

Empa internal project "SUISSE-battery"

Swiss National ScienceFoundation [grant number 200021_172764]

Joint Empa-Fraunhofer ISC project ”IE4B”under the ICON funding line

History

Email Address of Submitting Author

abdessalem.aribia@empa.ch

Institution

Empa – Swiss Federal Laboratories for Materials Science and Technology

Country

Switzerland

ORCID For Submitting Author

0000-0002-5558-8345

Declaration of Conflict of Interest

The authors declare no conflict of interest.

Version Notes

Version 2 - Final Version

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