Chu Mihai, Huang Zhongyuan, Zhang Taolve, Wang Rui, Shao Tielei, Wang Chaoqi, Zhu Weiming, He Lunhua, Chen Jie, Zhao Wenguang, Xiao Yinguo
School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
ACS Appl Mater Interfaces. 2021 May 5;13(17):19950-19958. doi: 10.1021/acsami.1c00755. Epub 2021 Apr 23.
Ni-rich layered cathode materials are considered as promising electrode materials for lithium ion batteries due to their high energy density and low cost. However, the low rate performance and poor electrochemical stability hinder the large-scale application of Ni-rich layered cathodes. In this work, both the rate performance and the structural stability of the Ni-rich layered cathode LiNiCoMnO are significantly improved via the dual-site doping of Nb on both lithium and transition-metal sites, as revealed by neutron diffraction results. The dual-site Nb-doped LiNiCoMnO delivers 202.8 mAh·g with a capacity retention of 81% after 200 electrochemical cycles, which is much higher than that of pristine LiNiCoMnO. Moreover, a discharge capacity of 176 mAh·g at 10C rate illustrates its remarkable rate capability. Through in situ X-ray diffraction and electronic transport property measurements, it was demonstrated that the achievement of dual-site doping in the Ni-rich layered cathode can not only suppress the Li/Ni disordering and facilitate the lithium ion transport process but also stabilize the layered structure against local collapse and structural distortion. This work adopts a dual-site-doping approach to enhance the electrochemical performance and structural stability of Ni-rich cathode materials, which could be extended as a universal modification strategy to improve the electrochemical performance of other cathode materials.
富镍层状正极材料因其高能量密度和低成本而被认为是锂离子电池很有前景的电极材料。然而，低倍率性能和较差的电化学稳定性阻碍了富镍层状正极的大规模应用。在这项工作中，通过在锂位点和过渡金属位点上进行铌的双位点掺杂，富镍层状正极LiNiCoMnO的倍率性能和结构稳定性均得到显著改善，中子衍射结果表明了这一点。双位点铌掺杂的LiNiCoMnO在200次电化学循环后提供202.8 mAh·g的容量，容量保持率为81%，远高于原始LiNiCoMnO。此外，在10C倍率下176 mAh·g的放电容量说明了其卓越的倍率性能。通过原位X射线衍射和电子传输性能测量表明，在富镍层状正极中实现双位点掺杂不仅可以抑制Li/Ni无序化并促进锂离子传输过程，还可以稳定层状结构以防止局部坍塌和结构畸变。这项工作采用双位点掺杂方法来提高富镍正极材料的电化学性能和结构稳定性，这可以作为一种通用的改性策略来扩展，以改善其他正极材料的电化学性能。
