Liu Qun, Xie Te, Xie Qingshui, He Wei, Zhang Yinggan, Zheng Hongfei, Lu Xiangjun, Wei Wensheng, Sa Baisheng, Wang Laisen, Peng Dong-Liang
State Key Laboratory for Physical Chemistry of Solid Surfaces, Fujian Key Laboratory of Materials Genome, College of Materials, Xiamen University, Xiamen 361005, China.
Key Laboratory of Functional Materials and Applications of Fujian Province, School of Material Science and Engineering, Xiamen University of Technology, Xiamen 361024, China.
ACS Appl Mater Interfaces. 2021 Feb 24;13(7):8239-8248. doi: 10.1021/acsami.0c19040. Epub 2021 Feb 8.
Lithium-rich manganese-based (LRM) layered oxides are considered as one of the most promising cathode materials for next-generation high-energy-density lithium-ion batteries (LIBs) because of their high specific capacity (>250 mAh g). However, they also go through severe capacity decay, serious voltage fading, and poor rate capability during cycling. Herein, a multiscale deficiency integration, including surface coating, subsurface defect construction, and bulk doping, is realized in a LiMnNiCoO cathode material by facile Na-rich engineering through a sol-gel method. This multiscale design can significantly improve the bulk and surface structural stability and diffusion rate of Li ions of electrode materials. Specifically, an outstanding specific capacity of 201 mAh g is delivered at 1C of the designed cathode material after 400 cycles, relating to a large capacity retention of 89.0%. Meanwhile, the average voltage is retained up to 3.13 V with a large voltage retention of 89.6% and the energy density is maintained at 627.4 Wh kg. In situ X-ray diffraction (XRD), ex situ transmission electron microscopy (TEM) investigations, and density functional theory (DFT) calculations are conducted to explain the greatly enhanced electrochemical properties of a LRM cathode. We believe that this strategy would be a meaningful reference of LRM cathode materials for the research in the future.
富锂锰基（LRM）层状氧化物因其高比容量（>250 mAh g）而被认为是下一代高能量密度锂离子电池（LIBs）最有前景的正极材料之一。然而，它们在循环过程中也会经历严重的容量衰减、严重的电压衰减和较差的倍率性能。在此，通过溶胶-凝胶法采用简便的富钠工程在LiMnNiCoO正极材料中实现了多尺度缺陷整合，包括表面包覆、次表面缺陷构建和体相掺杂。这种多尺度设计可以显著提高电极材料的体相和表面结构稳定性以及锂离子扩散速率。具体而言，所设计的正极材料在1C倍率下经过400次循环后具有201 mAh g的出色比容量，容量保持率高达89.0%。同时，平均电压保持在3.13 V，电压保持率高达89.6%，能量密度维持在627.4 Wh kg。通过原位X射线衍射（XRD）、非原位透射电子显微镜（TEM）研究以及密度泛函理论（DFT）计算来解释LRM正极电化学性能的大幅提升。我们相信这种策略将为未来LRM正极材料的研究提供有意义的参考。
