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Title: Structural Studies of Capacity Activation and Reduced Voltage Fading in Li-Rich, Mn-Ni-Fe Composite Oxide Cathode

Authors:
ORCiD logo; ORCiD logo; ORCiD logo
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
DOE - BASIC ENERGY SCIENCES
OSTI Identifier:
1417390
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the Electrochemical Society; Journal Volume: 165; Journal Issue: 2
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Aryal, Shankar, Timofeeva, Elena V., and Segre, Carlo U. Structural Studies of Capacity Activation and Reduced Voltage Fading in Li-Rich, Mn-Ni-Fe Composite Oxide Cathode. United States: N. p., 2018. Web. doi:10.1149/2.0031802jes.
Aryal, Shankar, Timofeeva, Elena V., & Segre, Carlo U. Structural Studies of Capacity Activation and Reduced Voltage Fading in Li-Rich, Mn-Ni-Fe Composite Oxide Cathode. United States. doi:10.1149/2.0031802jes.
Aryal, Shankar, Timofeeva, Elena V., and Segre, Carlo U. Mon . "Structural Studies of Capacity Activation and Reduced Voltage Fading in Li-Rich, Mn-Ni-Fe Composite Oxide Cathode". United States. doi:10.1149/2.0031802jes.
@article{osti_1417390,
title = {Structural Studies of Capacity Activation and Reduced Voltage Fading in Li-Rich, Mn-Ni-Fe Composite Oxide Cathode},
author = {Aryal, Shankar and Timofeeva, Elena V. and Segre, Carlo U.},
abstractNote = {},
doi = {10.1149/2.0031802jes},
journal = {Journal of the Electrochemical Society},
number = 2,
volume = 165,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2018},
month = {Mon Jan 01 00:00:00 EST 2018}
}
  • We find that the electrochemical rate performance and capacity retention of the “layered–layered” lithium rich Li 1.2Mn 0.525Ni 0.175Co 0.1O 2(Li-rich NMC) material are significantly improved by a nanometer layer coating of a lithium conducting solid electrolyte, lithium phosphorus oxynitride (LiPON). The LiPON layer is deposited on the Li-rich NMC particles by the RF-magnetron sputtering method. The presence of the LiPON layer provides interfacial stability under high current (rate) and voltage cycling conditions and thereby improves the capacity retention over cycle life compared to pristine or uncoated Li-rich NMC. Specifically, the LiPON coated Li-rich NMC composite electrode showed stable reversiblemore » capacities of >275 mAh g -1 when cycled to 4.9 V for more than 300 cycles, and showed at least threefold improvements in the rate performance compared to the uncoated electrode compositions. Increasing the LiPON layer thickness beyond a few nanometers leads to capacity fade due to increasing electronic resistance. Lastly, detailed microstructural and electrochemical impedance spectroscopy studies are undertaken to characterize and understand the role of LiPON in improving the interfacial stability and electrochemical activity at the interface.« less
  • Pristine and cycled layered structure cathode of Li[Li0.2Ni0.2M0.6]O2 samples are characterized by aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy. These analyses provide new insights on capacity/voltage fading mechanism of Li[Li0.2Ni0.2M0.6]O2. Sponge-like structure and fragment pieces were found on the surface of cathode after cycling. Mn2+ species and reduced Li content in the fragments caused significant capacity loss. These results also reveal the functional mechanism of surface coatings, e.g. AlF3, which can protect the electrode from etching by acidic species in the electrolyte, suppress cathode degradation and improve long-term cycling stability.
  • Making all-electric vehicles (EVs) commonplace in transportation applications will require affordable high-power and high-energy-density lithium-ion batteries (LIBs). The quest for suitable cathode materials to meet this end has currently plateaued with the discovery of high-voltage (≥4.7 V vs. Li +), high capacity (~250 mAh/g) lithium–manganese-rich (LMR) layered composite oxides. In spite of the promise of LMR oxides in high-energy-density LIBs, an irreversible structural change has been identified in this work that is governed by the formation of a ‘permanent’ spin-glass type magnetically frustrated phase indicating a dominant AB 2O 4 (A = Li, B = Mn) type spinel after amore » short-term lithium deintercalation (charging) and intercalation (discharging) process. Furthermore, reduction of transition metal (Mn) ions from the 4+ state (pristine LMR) to 3+ (cycled LMR), which alters the intercalation redox chemistry and suggests the presence of ‘unfilled’ lithium vacancies and/or oxygen vacancies in the lattice after cycling, has presented a major stumbling block. Finally, these situations result in both loss of capacity and fading of the voltage profile, and these combined effects significantly reduce the high energy density over even short-term cycling.« less