Toward a stabilized lattice framework and surface structure of layered lithium-rich cathode materials with Ti modification.
Toward a stabilized lattice framework and surface structure of layered lithium-rich cathode materials with Ti modification.
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DOI：
10.1039/c5cp00853k
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发表时间：
2015-04
期刊：
影响因子：
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通讯作者：
Sihui Wang;Yixiao Li;Jue Wu;Bizhu Zheng;M. J. McDonald;Yong Yang
中科院分区：
文献类型：
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作者：
Sihui Wang;Yixiao Li;Jue Wu;Bizhu Zheng;M. J. McDonald;Yong Yang
层状富锂氧化物存在电压衰减快、能量密度循环稳定性差等严重缺点，极大地阻碍了其实际应用。在充放电过程中制备稳定的层状富锂氧化物骨架对于解决上述问题至关重要。在这项工作中，我们证明钛改性是实现这一具有双功能目标的有前途的方法。例如，它能够取代晶格骨架中的Mn并形成稳定的表面层。因此，Ti 改性的 Li1.2Mn0.54-xTixNi0.13Co0.13O2 (x = 0.04、0.08 和 0.15) 材料在循环过程中能量密度的保留得到改善。 dQ/dV 曲线的演变表明，由于骨架中引入了强 Ti-O 键，层状/尖晶石相变受到抑制。此外，SEM、TEM 和 EIS 结果证实，与无 Ti 材料相比，Ti 改性 Li1.2Mn0.54-xTixNi0.13Co0.13O2 (x = 0.04、0.08 和 0.15) 材料上形成了更均匀、更稳定的界面层。富锂氧化物上稳定的界面层也有利于进一步减少副反应，从而产生稳定的界面层电阻。因此，材料循环性能的改善归因于更稳定的骨架和Ti改性增强的电极/电解质界面的贡献。
Layered lithium-rich oxides have several serious shortcomings such as fast voltage fading and poor cyclic stability of energy density which greatly hinder their practical applications. Fabrication of a stable framework of layered lithium-rich oxides during charging-discharging is crucial for addressing the above problems. In this work, we show that Ti modification is a promising way to realize this target with bifunctional roles. For example, it is able to substitute Mn in the lattice framework and form a stable surface layer. It therefore leads to an improved retention of energy density of the Ti-modified Li1.2Mn0.54-xTixNi0.13Co0.13O2 (x = 0.04, 0.08, and 0.15) materials during cycling. The evolution of dQ/dV curves show that the layered/spinel phase transformation is suppressed owing to the introduction of strong Ti-O bonds in the framework. In addition, SEM, TEM, and EIS results confirm that a more uniform and stable interface layer is formed on Ti-modified Li1.2Mn0.54-xTixNi0.13Co0.13O2 (x = 0.04, 0.08, and 0.15) materials compared with the Ti-free counterpart. The stable interface layer on the lithium-rich oxides is also beneficial for further reducing side reactions, resulting in stable interface layer resistance. Therefore, the improved cycling performance of the material is due to both contribution of the more stable framework and enhanced electrode/electrolyte interface by Ti modification.