Comparative study on the electronic structures and redox reactions in LiCrX2 and NaCrX2 (X = O and S)
| Autor: | Mei-ying Zheng, Zi-Zhong Zhu, Yong Yang, Yue-Wen He, Shunqing Wu, Xiaohong Shi |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Materials science
Magnetic moment General Chemical Engineering chemistry.chemical_element Charge (physics) Fermi surface 02 engineering and technology General Chemistry Electron 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Redox Cathode 0104 chemical sciences law.invention Ion chemistry law Physical chemistry Lithium 0210 nano-technology |
| Zdroj: | RSC Advances. 9:36867-36874 |
| ISSN: | 2046-2069 |
| DOI: | 10.1039/c9ra08224g |
| Popis: | LiCrO2 and NaCrO2 have been well-studied as cathode materials in lithium and sodium ion batteries, while the studies on LiCrS2 and NaCrS2 are relatively rare. In this work, a comparative study on the electronic structures and redox reactions in oxides (LiCrO2, NaCrO2) and sulfides (LiCrS2, NaCrS2) is performed. A first-principles method has been used to calculate the Bader charge transfer, the electronic structures and the magnetic moments during the entire delithiation or desodiation process. The Bader charge analysis suggests that all the S, O and Cr ions in LiCrX2 and NaCrX2 participate in the redox reactions, where the loss of electrons of S ions is clearly larger than that of O ions. Besides, the redox processes of Cr ions are of much less significance. It is noted that, in the sulfides, Cr ions even gain a small portion of electrons rather than losing electrons during the extraction of Li/Na ions. All the charge transfer happens between the S-3p/O-2p and the Cr-3d bands. The redox reactions of O or S ions originate from the energy levels of O/S being pushed towards/across the Fermi surface due to the strong p–d hybridization. |
| Databáze: | OpenAIRE |
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