Abstract
Electrolyte decomposition on cathode surfaces is an irreversible reaction that creates a passivation layer known as the cathode electrolyte interphase (CEI). Since the CEI can lead to increased internal resistance, accelerated electrode decomposition, and loss of lithium inventory, a deeper comprehension is important for developing improved batteries. Although several models of the CEI have been proposed, the actual structure is unknown. Here we report three-dimensional tomography revealing the atomic-scale interface structure and micron-scale structure of a LiMn2O4 electrode. Atom probe tomography is employed to provide critical new information on CEI structure and composition: a complex layered-mosaic architecture is found consisting of inner homogeneous MnxOy and MnFx layers (~9nm- and ~4nm-thick) and an outer 3nm-thick mosaic structure containing a number of different inorganic and organic compounds. The results are used to develop a realistic quantitative model of the main electrochemical processes. This approach provides a new means to explore electrode systems including the effects of coatings and electrolyte additives.
| Original language | English (US) |
|---|---|
| Article number | 100748 |
| Journal | Applied Materials Today |
| Volume | 20 |
| DOIs | |
| State | Published - Sep 2020 |
Funding
The authors gratefully acknowledge financial support from the Office of Naval Research ( ONR ) through the Research Grants N00014–17–1–2688 and N00014–19–1–2135. Atom-probe tomography was performed at the Northwestern University Center for Atom-Probe Tomography (NUCAPT). The LEAP tomograph at NUCAPT was purchased and upgraded with funding from NSF-MRI (DMR-0420532) and ONR-DURIP (N00014–0400798,N00014–0610539, N00014–0910781, N00014–1712870) grants. Instrumentation at NUCAPT was supported by the Initiative for Sustainability and Energy at Northwestern University (ISEN). This work made use of the MatCI Facility and the EPIC facility (NUANCE Center) at Northwestern University. NUCAPT, MatCI and NUANCE received support from the MRSEC program (NSF DMR-1121262) through Northwestern's Materials Research Center; NUCAPT and NUANCE also from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205). NUANCE received support from the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. The authors gratefully acknowledge financial support from the Office of Naval Research (ONR) through the Research Grants N00014?17?1?2688 and N00014?19?1?2135. Atom-probe tomography was performed at the Northwestern University Center for Atom-Probe Tomography (NUCAPT). The LEAP tomograph at NUCAPT was purchased and upgraded with funding from NSF-MRI (DMR-0420532) and ONR-DURIP (N00014?0400798,N00014?0610539, N00014?0910781, N00014?1712870) grants. Instrumentation at NUCAPT was supported by the Initiative for Sustainability and Energy at Northwestern University (ISEN). This work made use of the MatCI Facility and the EPIC facility (NUANCE Center) at Northwestern University. NUCAPT, MatCI and NUANCE received support from the MRSEC program (NSF DMR-1121262) through Northwestern's Materials Research Center; NUCAPT and NUANCE also from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205). NUANCE received support from the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. S.A. Barnett conceived and supervised the project. R. Scipioni assembled and tested the battery, developed and validated the equivalent circuit model (ECM) to fit the impedance data, performed FIB-SEM tomography and parameters determination for the ECM, and prepared the sample for APT analysis. R. Scipioni and D. Isheim performed APT characterization of the sample, critical analysis of the mass spectrum and APT images rendering. R. Scipioni and S.A. Barnett wrote the manuscript. All authors discussed the data and contributed to the manuscript.
Keywords
- Atom probe tomography
- Cathode electrolyte interphase
- Electrochemical impedance spectroscopy
- Multi-scale characterization
ASJC Scopus subject areas
- General Materials Science
