当前位置: X-MOL 学术J. Power Sources › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Uncovering the role of Nb modification in improving the structure stability and electrochemical performance of LiNi0.6Co0.2Mn0.2O2 cathode charged at higher voltage of 4.5 V
Journal of Power Sources ( IF 9.2 ) Pub Date : 2017-11-15 , DOI: 10.1016/j.jpowsour.2017.11.037
Siyang Liu , Xiang Chen , Jiayue Zhao , Junming Su , Congcong Zhang , Tao Huang , Jianhua Wu , Aishui Yu

Ni-rich cathode materials attract ongoing interest due to their high specific capacity (∼200 mAh g−1). However, these materials suffer rapid capacity fading when charged to a high voltage and cycled at elevated temperature. In this study, we propose a facile method to reconstruct the surface structure of LiNi0.6Co0.2Mn0.2O2 via Nb modification, which integrates the merits of partial Nb5+ doping in the pristine structure and surface Li3NbO4 coating. The obtained results from Rietveld refinement and high resolution transmission electron microscopy confirm that Nb5+ is partially doped into Li+ sites within the surface lattice. Further ex-situ powder X-ray diffraction and kinetic analysis using electrochemical impedance spectroscopy reveal that Nb modification stabilizes the layered structure and facilitates the charge transfer process. Owing to the robust surface structure, 1 mol% Nb modified LiNi0.6Co0.2Mn0.2O2 delivers a discharge capacity of 160.9 mAh g−1 with 91% capacity retention after 100 cycles at 3.0–4.5 V, whereas the discharge capacity of the pristine sample drops to 139.6 mAh g−1, corresponding to 78% of its initial value. The presence of Nb5+ in the Li layer exhibits positive effects on stability of layered structure, and the surface Li3NbO4 coating layer increases interfacial stability, which results in superior electrochemical performance.



中文翻译:

揭示Nb改性在改善以4.5 V较高电压充电的LiNi 0.6 Co 0.2 Mn 0.2 O 2阴极的结构稳定性和电化学性能中的作用

富镍阴极材料因其高比容量(约200 mAh g -1)而引起了人们的持续关注。但是,这些材料在充电至高电压并在高温下循环时会遭受快速的容量衰减。在这项研究中,我们提出了一种通过Nb改性来重建LiNi 0.6 Co 0.2 Mn 0.2 O 2的表面结构的简便方法,该方法结合了原始结构中部分Nb 5+掺杂和表面Li 3 NbO 4涂层的优点。Rietveld精炼和高分辨率透射电子显微镜获得的结果证实,Nb 5+被部分掺杂到Li +中表面晶格内的位点。进一步的异位粉末X射线衍射和使用电化学阻抗谱的动力学分析表明,Nb改性可稳定层状结构并促进电荷转移过程。由于其坚固的表面结构,1 mol%Nb改性的LiNi 0.6 Co 0.2 Mn 0.2 O 2的放电容量为160.9 mAh g -1,在3.0-4.5 V下循环100次后,其容量保持率为91%。原始样品降至139.6 mAh g -1,相当于其初始值的78%。Nb 5+的存在Li层中的Li 3+对层状结构的稳定性具有积极作用,并且表面Li 3 NbO 4涂层增加了界面稳定性,这导致优异的电化学性能。

更新日期:2017-11-15
down
wechat
bug