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 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, 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 language | American English |
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Journal | Advanced Energy Materials |
Volume | 7 |
Issue number | 18 |
DOIs | |
State | Published - 20 Sep 2017 |
Keywords
- ammonia treatment
- cathodes
- lithium-ion batteries
- lithium-rich materials
- stabilization
- voltage fade
All Science Journal Classification (ASJC) codes
- General Materials Science
- Renewable Energy, Sustainability and the Environment