Zhang Yue, Jia Dianzeng, Tang Yakun, Huang Yudai, Pang Weikong, Guo Zaiping, Zhou Zhen
Key Laboratory of Energy Materials Chemistry, Ministry of Education, Institute of Applied Chemistry, Xinjiang University, Xinjiang, Urumqi, 830046, China.
Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW, 2522, Australia.
Small. 2018 Jul;14(27):e1704354. doi: 10.1002/smll.201704354. Epub 2018 Jun 3.
Layered lithium transition-metal oxides, with large capacity and high discharge platform, are promising cathode materials for Li-ion batteries. However, their high-rate cycling stability still remains a large challenge. Herein, hierarchical LiNi Co Mn O polyhedron assemblies are obtained through in situ chelation of transition metal ions (Ni , Co , and Mn ) with amide groups uniformly distributed along the backbone of modified polyacrylonitrile chains to achieve intimate mixing at the atomic level. The assemblies exhibit outstanding electrochemical performances: superior rate capability, high volumetric energy density, and especially ultralong high-rate cyclability, due to the superiority of unique hierarchical structures. The polyhedrons with exposed active crystal facets provide more channels for Li diffusion, and meso/macropores serve as access shortcuts for fast migration of electrolytes, Li and electrons. The strategy proposed in this work can be extended to fabricate other mixed transition metal-based materials for advanced batteries.
具有大容量和高放电平台的层状锂过渡金属氧化物是很有前景的锂离子电池正极材料。然而，它们的高倍率循环稳定性仍然是一个巨大的挑战。在此，通过过渡金属离子（Ni、Co和Mn）与沿改性聚丙烯腈链主链均匀分布的酰胺基团进行原位螯合，获得了分级LiNiCoMnO多面体组装体，以实现原子水平的紧密混合。由于独特的分级结构的优势，这些组装体表现出优异的电化学性能：卓越的倍率性能、高体积能量密度，尤其是超长的高倍率循环稳定性。具有暴露活性晶面的多面体为锂扩散提供了更多通道，而介孔/大孔则作为电解质、锂和电子快速迁移的通道捷径。这项工作中提出的策略可以扩展到制备用于先进电池的其他混合过渡金属基材料。
