High‐Temperature Treatment of Li‐Rich Cathode Materials with Ammonia: Improved Capacity and Mean Voltage Stability during Cycling |
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| Authors: | 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 |
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| Affiliation: | 1. Department of Chemistry, Faculty of Exact Sciences, Bar‐Ilan University, Ramat‐Gan, Israel;2. Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, NY, USA;3. Wolfson Applied Materials Research Center, Tel‐Aviv University, Tel‐Aviv, Israel;4. Department of Materials Engineering, Ben Gurion University of the Negev, Beer‐Sheva, Israel;5. BASF SE, Rheinland‐Pfalz, Germany |
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| Abstract: | Li‐rich electrode materials of the family x Li2MnO3·(1?x )LiNia Cob Mnc O2 (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. |
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| Keywords: | ammonia treatment cathodes lithium‐ion batteries lithium‐rich materials stabilization voltage fade |
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