Abstract
The exploding electric-vehicle market requires cost-effective high-energy materials for rechargeable lithium batteries. The manganese-rich spinel oxide LiNi0.5Mn1.5O4 (LNMO) can store a capacity greater than 200 mAh g−1 based on the multi-cation (Ni2+/Ni4+ and Mn3+/Mn4+) redox centers. However, its practical capacity is limited to Ni2+/Ni4+ redox (135 mAh g−1) due to the poor reversibility of Mn3+/Mn4+ redox. This instability is generally attributed to the Jahn–Teller distortion of Mn3+ and its disproportionation, which leads to severe Mn dissolution. Herein, for the first time, the excellent reversibility of Mn3+/Mn4+ redox within 2.3–4.3 V is demonstrated, requiring revisiting the previous theory. LNMO loses capacity only within a wide voltage range of 2.3–4.9 V. It is revealed that a dynamic evolution of the electrochemical interface, for example, potential-driven rocksalt phase formation and decomposition, repeatedly occurs during cycling. The interfacial evolution induces electrolyte degradation and surface passivation, impeding the charge-transfer reactions. It is further demonstrated that stabilizing the interface by electrolyte modification extends the cycle life of LNMO while using the multi-cation redox, enabling 71.5% capacity retention of LNMO after 500 cycles. The unveiled dynamic oxide interface will propose a new guideline for developing Mn-rich cathodes by realizing the reversible Mn redox.
Original language | English |
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Article number | 2202049 |
Journal | Advanced Energy Materials |
Volume | 12 |
Issue number | 46 |
DOIs | |
Publication status | Published - 2022 Dec 8 |
Bibliographical note
Publisher Copyright:© 2022 The Authors. Advanced Energy Materials published by Wiley-VCH GmbH.
Keywords
- EC-free electrolytes
- Mn-rich cathodes
- cathode-electrolyte interfaces
- multi-cation redox
- rechargeable Li batteries
- spinel oxides
- surface reconstruction
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- General Materials Science