| Autor: |
Kondo, Tatsuya, Matsumura, Keisuke, Rozier, Patrick, Simon, Patrice, Machida, Kenji, Takeda, Sekihiro, Ishimoto, Shuichi, Tamamitsu, Kenji, Iwama, Etsuro, Naoi, Wako, Naoi, Katsuhiko |
| Zdroj: |
Chemistry of Materials; March 2024, Vol. 36 Issue: 5 p2495-2507, 13p |
| Abstrakt: |
This study explores the potential of titanium ion (Ti4+) substitution in γ-Li3VO4(γ-LVO) as an anode material for high-energy supercapacitors. A series of Li3+xV1–xTixO4(x= 0, 0.05, 0.10, 0.15, and 0.20) are systematically synthesized to vary the Ti-substitution ratio within LVO, and their crystal phases were analyzed using X-ray diffraction (XRD). Additionally, the reactivity of Ti during charge–discharge cycles is assessed by monitoring in situ X-ray absorption fine structure (XAFS) spectral changes. Quenching methods and XRD measurements quantitatively reveal that substituting 20 atom % of V5+with Ti4+achieves a single-phase γ-LVO, distinct from the nonsubstituted LVO (β-phase LVO). The Ti-substituted γ-phase LVO electrode displays a supercapacitor-like voltage curve and exceptional high-power performance during charge–discharge tests, benefiting from its high ionic conductivity stemming from the LISICON (Lithium Super Ionic CONductor) crystal structure. Furthermore, the Ti-substituted γ-phase LVO electrode exhibits an impressive rate capability, retaining 50% of its capacity at a very high current density of 2 A g–1(10C-rate), while the nonsubstituted LVO retained only 13% under the same conditions. GITT analysis confirms a 100-fold higher Li+diffusion coefficient for the Ti-substituted γ-phase LVO electrode. A novel approach is employed to examine the kinetic effects of Ti substitution on γ-phase stabilization: halting or quenching the γ → β phase transition during cooling using liquid nitrogen, coupled with XRD measurements, facilitates a quantitative evaluation of the phase transition rate. The primary goal of this study is to conduct a comprehensive assessment of the crystal structure and its stability by taking advantage of the excellent traceability of the Ti element through X-ray measurements to achieve this aim. |
| Databáze: |
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