| Autor: |
Liu, H, Qian, D, Verde, MG, Zhang, M, Baggetto, L, An, K, Chen, Y, Carroll, KJ, Lau, D, Chi, M, Veith, GM, Meng, YS |
| Jazyk: |
angličtina |
| Rok vydání: |
2015 |
| Předmět: |
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| Zdroj: |
Liu, H; Qian, D; Verde, MG; Zhang, M; Baggetto, L; An, K; et al.(2015). Understanding the Role of NH4F and Al2O3 Surface Co-modification on Lithium-Excess Layered Oxide Li1.2Ni0.2Mn0.6O2. ACS Applied Materials and Interfaces, 7(34), 19189-19200. doi: 10.1021/acsami.5b04932. UC San Diego: Retrieved from: http://www.escholarship.org/uc/item/1794v0bp |
| Popis: |
© 2015 American Chemical Society.In this work we prepared Li1.2Ni0.2Mn0.6O2 (LNMO) using a hydroxide co-precipitation method and investigated the effect of co-modification with NH4F and Al2O3. After surface co-modification, the first cycle Coulombic efficiency of Li1.2Ni0.2Mn0.6O2 improved from 82.7% to 87.5%, and the reversible discharge capacity improved from 253 to 287 mAh g-1 at C/20. Moreover, the rate capability also increased significantly. A combination of neutron diffraction (ND), high-resolution transmission electron microscopy (HRTEM), aberration-corrected scanning transmission electron microscopy (a-STEM)/electron energy loss spectroscopy (EELS), and X-ray photoelectron spectroscopy (XPS) revealed the changes of surface structure and chemistry after NH4F and Al2O3 surface co-modification while the bulk properties showed relatively no changes. These complex changes on the material's surface include the formation of an amorphous Al2O3 coating, the transformation of layered material to a spinel-like phase on the surface, the formation of nanoislands of active material, and the partial chemical reduction of surface Mn4+. Such enhanced discharge capacity of the modified material can be primarily assigned to three aspects: decreased irreversible oxygen loss, the activation of cathode material facilitated with preactivated Mn3+ on the surface, and stabilization of the Ni-redox pair. These insights will provide guidance for the surface modification in high-voltage-cathode battery materials of the future. (Figure Presented). |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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