Abstract
The high-temperature operation of Li-ion batteries is highly dependent on the stability of the cathode electrolyte interphase (CEI) formed during lithiation−delithiation reactions. However, knowledge on the nature of the CEI is limited and its stability under extreme temperatures is not well understood. Therefore, herein, we investigate a proof-of-concept study on stabilizing CEI on model LiNi0.33Mn0.33Co0.33O2 (NMC333) at an extreme operation condition of 100 °C using the thermally stable pyrrolidinium-based ionic liquid electrolyte. The electrochemical lithiation−delithiation reactions at 100 °C and the CEI evolution upon different cycling conditions are investigated. Further, the depth-dependent CEI chemistry was investigated using energy-tunable synchrotron-based hard X-ray photoelectron spectroscopy (HAXPES). The results reveal that the high-temperature operation accelerated the CEI formation compared to room temperature, and the surface of the interphase layer is rich in boron-based inorganic moieties than the deeper surface. Further, bulk-sensitive X-ray absorption spectroscopy (XAS) was used to investigate the transition-metal redox contributors during high-temperature electrochemical reactions; similar to room temperature, the Ni2+/4+ redox couple is the only charge-compensating redox couple during high-temperature operation. Finally, the physical nature of the conformal CEI on the cathode particles was visualized with high-resolution transmission electron microscopy, which confirms that the significant degradation of cathode particles without conformal CEI is due to the transformation of a layer-to-spinel formation at extreme temperature. In this study, understanding this high-temperature interfacial chemistry of NMC cathodes through advanced spectroscopy and microscopy will shed light on transforming the ambient-temperature Li-ion chemistry into high-temperature applications.
| Original language | English |
|---|---|
| Pages (from-to) | 4587-4601 |
| Number of pages | 15 |
| Journal | Chemistry of Materials |
| Volume | 34 |
| Issue number | 10 |
| DOIs | |
| State | Published - May 24 2022 |
Funding
This material was based upon work supported by the National Science Foundation under grant number 1751472. The authors also acknowledge funding support from the Advanced Energy Consortium (AEC) (BEG14\u221202). http://www.beg.utexas.edu/aec/partners companies include BHP, ExxonMobil, U.S. Department of Energy, Repsol, Sandia National Labs, and Total. This research used resources of the National Synchrotron Light Source II (NSLS-II), a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract DE-SC0012704. The HAXPES measurements were performed at the National Institute of Standards and Technology (NIST) beamline SST-2 in the NSLS-II. This research also used resources of the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704. This research used resources of the Advanced Photon Source (APS), an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. The authors acknowledge the Lumigen Instrument Centre at Wayne State University for the use of XRD (NSF: MRI 1427926) facility. This material was based upon work supported by the National Science Foundation under grant number 1751472. The authors also acknowledge funding support from the Advanced Energy Consortium (AEC) (BEG14\u201302). http://www.beg.utexas.edu/aec/partners companies include BHP, ExxonMobil, U.S. Department of Energy, Repsol, Sandia National Labs, and Total. This research used resources of the National Synchrotron Light Source II (NSLS-II), a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract DE-SC0012704. The HAXPES measurements were performed at the National Institute of Standards and Technology (NIST) beamline SST-2 in the NSLS-II. This research also used resources of the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704. This research used resources of the Advanced Photon Source (APS), an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. The authors acknowledge the Lumigen Instrument Centre at Wayne State University for the use of XRD (NSF: MRI 1427926) facility.