The roles of atomic layer deposition (ALD) coatings on the stability of FeF3 Na-ion cathodes

Z. Sun; M. Boebinger; M. Liu; P. Lu; W. Fu; B. Wang; A. Magasinski; Y. Zhang; Y. Huang; AY Y. Song; M. T. McDowell; G. Yushin

doi:10.1016/j.jpowsour.2021.230281

The roles of atomic layer deposition (ALD) coatings on the stability of FeF₃ Na-ion cathodes

Z. Sun, M. Boebinger, M. Liu, P. Lu, W. Fu, B. Wang, A. Magasinski, Y. Zhang, Y. Huang, AY Y. Song, M. T. McDowell, G. Yushin

Research output: Contribution to journal › Article › peer-review

12 Scopus citations

Abstract

Atomic layer deposition (ALD) has been used to stabilize Na-ion battery (SIB) electrodes but the role of ALD coatings and the mechanism of the improvements remain unclear, particularly in conversion-type cathodes. Here, we study for the first time the influence of alumina and titania (Al₂O₃ and TiO₂) ALD coatings on conversion FeF₃ cathodes in SIBs. Post-mortem analysis revealed that active material in both samples developed a small fraction of iron oxyfluoride (FeOF) during cycling. Similarly, the in-situ fluorination of both ALD oxide coatings led to the formation of aluminum and titanium oxyfluorides. The aluminum oxyfluoride formed a conformal passivating layer that was well adhered to the cathode electrolyte interphase (CEI). As a result, the Al₂O₃ coating reduced direct contact between the active material and the liquid electrolyte, minimized active material dissolution and significantly improved the overall electrochemical performance of FeF₃ cathodes in SIBs. In contrast, the in-situ fluorination of the TiO₂ ALD layer failed to produce a defect-free passivating layer and was inefficient in preventing side reactions, leading to the inferior performance.

Original language	English
Article number	230281
Journal	Journal of Power Sources
Volume	507
DOIs	https://doi.org/10.1016/j.jpowsour.2021.230281
State	Published - Sep 30 2021
Externally published	Yes

Funding

This work was supported by ARO (Grant No. W911NF-17-1-0053 ). The authors thank Dr. Yong Ding (staff in Materials Characterization Facility, Georgia Institute of Technology) for the guidance in TEM imaging and Oak Ridge National Lab for the support of in-situ TEM characterization. M.G.B. acknowledges support from the DOE Office of Science Graduate Student Research Program for research performed at Oak Ridge National Laboratory. A portion of this research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. M. L. acknowledge additional fellowship support of China Scholarship Council .

Funders	Funder number
Army Research Office	W911NF-17-1-0053
Office of Science
Oak Ridge National Laboratory
China Scholarship Council

Keywords

ALD coatings
Conversion cathodes
FeF
In-situ TEM
Na-ion batteries

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1016/j.jpowsour.2021.230281

Cite this

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title = "The roles of atomic layer deposition (ALD) coatings on the stability of FeF3 Na-ion cathodes",

abstract = "Atomic layer deposition (ALD) has been used to stabilize Na-ion battery (SIB) electrodes but the role of ALD coatings and the mechanism of the improvements remain unclear, particularly in conversion-type cathodes. Here, we study for the first time the influence of alumina and titania (Al2O3 and TiO2) ALD coatings on conversion FeF3 cathodes in SIBs. Post-mortem analysis revealed that active material in both samples developed a small fraction of iron oxyfluoride (FeOF) during cycling. Similarly, the in-situ fluorination of both ALD oxide coatings led to the formation of aluminum and titanium oxyfluorides. The aluminum oxyfluoride formed a conformal passivating layer that was well adhered to the cathode electrolyte interphase (CEI). As a result, the Al2O3 coating reduced direct contact between the active material and the liquid electrolyte, minimized active material dissolution and significantly improved the overall electrochemical performance of FeF3 cathodes in SIBs. In contrast, the in-situ fluorination of the TiO2 ALD layer failed to produce a defect-free passivating layer and was inefficient in preventing side reactions, leading to the inferior performance.",

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author = "Z. Sun and M. Boebinger and M. Liu and P. Lu and W. Fu and B. Wang and A. Magasinski and Y. Zhang and Y. Huang and Song, {AY Y.} and McDowell, {M. T.} and G. Yushin",

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AU - Fu, W.

AU - Wang, B.

AU - Magasinski, A.

AU - Zhang, Y.

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AU - Yushin, G.

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N2 - Atomic layer deposition (ALD) has been used to stabilize Na-ion battery (SIB) electrodes but the role of ALD coatings and the mechanism of the improvements remain unclear, particularly in conversion-type cathodes. Here, we study for the first time the influence of alumina and titania (Al2O3 and TiO2) ALD coatings on conversion FeF3 cathodes in SIBs. Post-mortem analysis revealed that active material in both samples developed a small fraction of iron oxyfluoride (FeOF) during cycling. Similarly, the in-situ fluorination of both ALD oxide coatings led to the formation of aluminum and titanium oxyfluorides. The aluminum oxyfluoride formed a conformal passivating layer that was well adhered to the cathode electrolyte interphase (CEI). As a result, the Al2O3 coating reduced direct contact between the active material and the liquid electrolyte, minimized active material dissolution and significantly improved the overall electrochemical performance of FeF3 cathodes in SIBs. In contrast, the in-situ fluorination of the TiO2 ALD layer failed to produce a defect-free passivating layer and was inefficient in preventing side reactions, leading to the inferior performance.

AB - Atomic layer deposition (ALD) has been used to stabilize Na-ion battery (SIB) electrodes but the role of ALD coatings and the mechanism of the improvements remain unclear, particularly in conversion-type cathodes. Here, we study for the first time the influence of alumina and titania (Al2O3 and TiO2) ALD coatings on conversion FeF3 cathodes in SIBs. Post-mortem analysis revealed that active material in both samples developed a small fraction of iron oxyfluoride (FeOF) during cycling. Similarly, the in-situ fluorination of both ALD oxide coatings led to the formation of aluminum and titanium oxyfluorides. The aluminum oxyfluoride formed a conformal passivating layer that was well adhered to the cathode electrolyte interphase (CEI). As a result, the Al2O3 coating reduced direct contact between the active material and the liquid electrolyte, minimized active material dissolution and significantly improved the overall electrochemical performance of FeF3 cathodes in SIBs. In contrast, the in-situ fluorination of the TiO2 ALD layer failed to produce a defect-free passivating layer and was inefficient in preventing side reactions, leading to the inferior performance.

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