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High‐Temperature Treatment of Li‐Rich Cathode Materials with Ammonia: Improved Capacity and Mean Voltage Stability during Cycling
Author(s) -
Erickson Evan M.,
Sclar Hadar,
Schipper Florian,
Liu Jing,
Tian Ruiyuan,
Ghanty Chandan,
Burstein Larisa,
Leifer Nicole,
Grinblat Judith,
Talianker Michael,
Shin JiYong,
Lampert Jordan K.,
Markovsky Boris,
Frenkel Anatoly I.,
Aurbach Doron
Publication year - 2017
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201700708
Subject(s) - materials science , x ray photoelectron spectroscopy , spinel , electrode , cathode , capacity loss , cycling , ammonia , analytical chemistry (journal) , lithium (medication) , chemical engineering , electrochemistry , metallurgy , chemistry , archaeology , organic chemistry , chromatography , engineering , history , medicine , endocrinology
Li‐rich electrode materials of the family x Li 2 MnO 3 ·(1− x )LiNi a Co b Mn c O 2 ( 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, 0.35Li 2 MnO 3 ·0.65LiNi 0.35 Mn 0.45 Co 0.20 O 2 , is exposed to NH 3 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 NH 3 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 CoO and MnO bonds, as well as formation of a surface spinel‐like structure. Additionally, Li + removal from the bulk causes the formation of surface LiOH, Li 2 CO 3 , and Li 2 O. These structural and surface changes can enhance the voltage and capacity stability of the Li‐rich material electrodes after moderate NH 3 treatment times of 1–2 h.