Uncovering the role of Nb modification in improving the structure stability and electrochemical performance of LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode charged at higher voltage of 4.5 V
| Autor: | Junming Su, Aishui Yu, Jiayue Zhao, Siyang Liu, Tao Huang, Jianhua Wu, Xiang Chen, Congcong Zhang |
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| Rok vydání: | 2018 |
| Předmět: |
Diffraction
Materials science Renewable Energy Sustainability and the Environment Rietveld refinement Doping Analytical chemistry Energy Engineering and Power Technology 02 engineering and technology engineering.material 010402 general chemistry 021001 nanoscience & nanotechnology Electrochemistry 01 natural sciences Cathode 0104 chemical sciences law.invention Dielectric spectroscopy Coating law engineering Electrical and Electronic Engineering Physical and Theoretical Chemistry 0210 nano-technology High-resolution transmission electron microscopy |
| Zdroj: | Journal of Power Sources. 374:149-157 |
| ISSN: | 0378-7753 |
| DOI: | 10.1016/j.jpowsour.2017.11.037 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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