High-Temperature Treatment of Li-Rich Cathode Materials with Ammonia: Improved Capacity and Mean Voltage Stability during Cycling

Evan M. Erickson, Hadar Sclar, Florian Schipper, Jing Liu, Ruiyuan Tian, Chandan Ghanty, Larisa Burstein, Nicole Leifer, Judith Grinblat, Michael Talianker, Ji Yong Shin, Jordan K. Lampert, Boris Markovsky, Anatoly I. Frenkel, Doron Aurbach

Research output: Contribution to journalArticlepeer-review

135 Scopus citations

Abstract

Li-rich electrode materials of the family xLi2MnO3·(1−x)LiNiaCobMncO2 (a + b + c = 1) suffer a voltage fade upon cycling that limits their utilization in commercial batteries despite their extremely high discharge capacity, ≈250 mA h g−1. Li-rich, 0.35Li2MnO3·0.65LiNi0.35Mn0.45Co0.20O2, is exposed to NH3 at 400 °C, producing materials with improved characteristics: enhanced electrode capacity and a limited average voltage fade during 100 cycles in half cells versus Li. Three main changes caused by NH3 treatment are established. First, a general bulk reduction of Co and Mn is observed via X-ray photoelectron spectroscopy and X-ray absorption near edge structure. Next, a structural rearrangement lowers the coordination number of CoO and MnO bonds, as well as formation of a surface spinel-like structure. Additionally, Li+ removal from the bulk causes the formation of surface LiOH, Li2CO3, and Li2O. These structural and surface changes can enhance the voltage and capacity stability of the Li-rich material electrodes after moderate NH3 treatment times of 1–2 h.

Original languageEnglish
JournalAdvanced Energy Materials
Volume7
Issue number18
DOIs
StatePublished - 20 Sep 2017

Bibliographical note

Publisher Copyright:
© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Funding

D.A. thanks and acknowledges BASF SE for funding. B.M. thanks Mr. Gregory Avrushenko for his help in maintaining the NH3 gas treatment apparatus and useful discussions. A.I.F. and J.L. acknowledge support by the U.S. National Science Foundation Grant No. CHE-1413937. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

FundersFunder number
DOE Office of Science
U.S. National Science FoundationCHE-1413937
U.S. Department of Energy
BASF
Office of Science
Argonne National LaboratoryDE-AC02-06CH11357

    Keywords

    • ammonia treatment
    • cathodes
    • lithium-ion batteries
    • lithium-rich materials
    • stabilization
    • voltage fade

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