Journal
MATERIALS TODAY
Volume 51, Issue -, Pages 15-26Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.mattod.2021.10.020
Keywords
Li-ion batteries; Li-rich layered cathodes; Oxygen redox activation; Composition design; Local structure modulation
Categories
Funding
- National Key Research and Development Program of China [2016YFB0100100]
- National Natural Science Foundation of China [21703271, 21773279]
- Natural Science Foundation of Ningbo [202003N4030]
- S&T Innovation 2025 Major Special Program of Ningbo [2018B10081]
- Zable endowed chair fund
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The study systematically investigated the structural characteristics of Li-rich cathode materials, discovering the sensitivity of oxygen redox activation to local Co coordination environments. Co ions were found to enhance the activation of Li2MnO3-like domains, leading to higher reversible capacity.
The Li-rich layered oxide is considered as one of the most promising cathode materials for high energy density batteries, due to its ultrahigh capacity derived from oxygen redox. Although incorporating over-stoichiometric Li into layered structure can generate Li2MnO3-like domain and enhance the oxygen redox activity thermodynamically, the fast and complete activation of the Li2MnO3-like domain remains challenging. Herein, we performed a systematic study on structural characteristics of Li-rich cathode materials to decipher the factors accounting for activation of oxygen redox. We reveal that the activation of Li-rich cathode materials is susceptible to local Co coordination environments. The Co ions can intrude into Li2MnO3-like domain and modulate the electronic structure, thereby facilitating the activation of Li-rich layered cathode materials upon first charging, leading to higher reversible capacity. In contrast, Li2MnO3-like domain hardly contains any Ni ions which contribute little to the activation process. The optimum composition design of this class of materials is discussed and we demonstrate a small amount of Co/Mn exchange in Li2MnO3-like domain can significantly promote the oxygen redox activation. Our findings highlight the vital role of Co ions in the activation of oxygen redox Li-rich layered cathode materials and provide new insights into the pathway toward achieving high-capacity Li-rich layered cathode materials.
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