Paving Pathways Toward Long-Life Graphite/LiNi0.5Mn1.5O4 Full Cells: Electrochemical and Interphasial Points of View
Paving Pathways Toward Long-Life Graphite/LiNi0.5Mn1.5O4 Full Cells: Electrochemical and Interphasial Points of View
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DOI：
10.1002/adfm.202203779
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发表时间：
2022-06-29
影响因子：
19
通讯作者：
Manthiram, Arumugam
中科院分区：
文献类型：
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作者：
Cui, Zehao;Zou, Feng;Manthiram, Arumugam
具有无钴且低镍含量的高压尖晶石正极材料LiNi₀.₅Mn₁.₅O₄（LNMO）因其高能量和功率密度、良好的热稳定性以及低成本，在锂离子电池领域颇具应用前景。然而，其高工作电压（约4.7 V）会导致电解液分解、严重的化学交叉以及电极 - 电解液界面（EEIs）恶化，从而阻碍了其实际应用可行性。本文证明，通过在含30 wt.%氟代碳酸乙烯酯的电解液中对石墨进行电化学预循环，可以构建一种坚固的富含LiF的人造固体电解质界面用于表面保护；另一方面，铁掺杂LNMO的电化学预锂化可在2.6 V的全电池电压下作为石墨的锂源。结果表明，使用经修饰电极的全电池可提供129 mA h g⁻¹的高容量，在200次循环后具有93%的优异容量保持率，远远优于使用未处理电极的全电池（初始容量为120 mA h g⁻¹，保持率为78%）。最后，基于本研究中对电化学修饰的启发以及对EEIs的深入分析，描绘了实现长寿命石墨||LNMO全电池的途径。
The high-voltage spinel cathode LiNi0.5Mn1.5O4 (LNMO) with no cobalt and low nickel content is promising for lithium-ion batteries due to its high energy and power densities, good thermal stability, and low cost. However, its high operating voltage (approximate to 4.7 V) results in a decomposition of the electrolyte, severe chemical crossover, and deterioration of electrode-electrolyte interphases (EEIs), hindering its practical viability. It is demonstrated here that by electrochemically pre-cycling the graphite in an electrolyte containing 30 wt.% fluoroethylene carbonate, a robust LiF-rich artificial solid electrolyte interphase can be constructed for surface protection; on the other hand, an electrochemical pre-lithiation of Fe-doped LNMO serves as a lithium source for graphite at a full-cell voltage of 2.6 V. As a result, the full cells with the as-modified electrodes deliver a high capacity of 129 mA h g(-1) with an excellent capacity retention of 93% after 200 cycles, vastly outperforming the full cells with fresh electrodes (120 mA h g(-1) initial capacity with 78% retention). Finally, pathways toward long-life graphite||LNMO full cells are pictured based on the inspirations from the electrochemical modifications and in-depth analyses of the EEIs in this study.