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Preparation of (VCrMnNiCo)3O4 High Entropy Oxide by Hydrothermal Method for Li-Ion Battery Anode

Esmaeili, Mohammad Reza | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56986 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Sadrnezhaad, Khatiboleslam; Yoozbashizadeh, Hossein
  7. Abstract:
  8. High entropy oxides are a group of oxides which consist of five cations and are stable at high temperature. Since these materials have unique properties such as high ionic media, high capacity and cycle stability, they can be considered for use in lithium-ion batteries. In this regard, in this research, for the first time, the effect of vanadium element in oxide with high entropy for use as anode in lithium-ion battery has been investigated. Therefore, (VCrMnNiCo)3O4 high entropy oxide has been synthesized by hydrothermal method and then the single-phase structure has been stabilized at 900°C. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) studies have shown that (VCrMnNiCo)3O4 high entropy oxide nanoparticles are well crystallized with spinel structure. Also, the results of electron dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) show that the cations are uniformly distributed in the structure. In order to investigate the cyclic performance of (VCrMnNiCo)3O4, the known high-entropy oxide (FeCrMnNiCo)3O4 was synthesized and the results were compared. The comparison of these two anode materials shows that the use of vanadium instead of iron in the oxide structure with high entropy, despite the reduction of the initial capacity, improves the kinetics and rate capability of the battery. The (VCrMnNiCo)3O4 anode has shown a reversible capacity of over 750 mAh/g at a current density of 0.5 mAh/g and retains more than 60% of its initial capacity with a columbic efficiency close to 100%. Also, the results of the electrochemical impedance analysis show that the diffusion coefficient of lithium ion in the anode (VCrMnNiCo)3O4 was equal to 5.7 × 10-14 cm2/s, which was 3.16 times higher than the (FeCrMnNiCo)3O4 sample
  9. Keywords:
  10. Lithium Ion Batteries ; Rate Capability ; High-Entropy Oxides ; Spinel Structure ; Cyclic Stability ; Hydrothermal Method

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