本研究以尖晶石結構的Fe₃V₃O₈作為鋰/鈉離子電池之負極材料，探討其在不同條件下的電化學性能與加磁場所引發之老化效應。樣品採用水熱法搭配高溫燒結法合成，並透過X-ray繞射（XRD）及X-ray吸收光譜（XAS）進行相純性、晶體結構與過渡金屬價數之分析。結果顯示，樣品中釩（V）主要以V³⁺ 存在，而鐵（Fe）則以Fe³⁺為主。
進一步由BET 分析顯示，樣品具有中孔結構及適當比表面積，有助於鋰/鈉離子嵌入與脫嵌反應。於充放電測試中，前三圈可清楚觀察到對應平台及初期 SEI膜的生成現象。為分析老化行為，本研究透過電化學阻抗譜（EIS）比較施加與未施加磁場（300 mT）下多圈次循環後的電化學特性變化。實驗結果顯示，施加磁場會提升SEI膜阻抗與電荷轉移阻抗，並降低電容行為的理想性，對鈉離子的擴散速率亦有抑制作用，顯示磁場可能對鈉離子電池中的離子傳輸與界面反應產生不利影響。然而，對於鋰離子系統而言，在某些條件下磁場則可能有助於提升離子擴散效率。

In this study, spinel-structured Fe₃V₃O₈ was employed as an anode material for lithium/sodium-ion batteries to investigate its electrochemical performance under various conditions, as well as the aging effects induced by an applied magnetic field. The samples were synthesized using a hydrothermal method followed by high-temperature sintering. X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) were employed to investigate the phase purity, crystal structure, and oxidation states of the transition metals. The results indicate that vanadium (V) predominantly exists in the V³⁺ state, while iron (Fe) mainly exhibits the Fe³⁺ valence state. BET analysis further revealed that the samples possess a mesoporous structure and a suitable specific surface area, which are favorable for lithium/sodium ion intercalation and deintercalation reactions. During the initial charge-discharge tests, distinct voltage plateaus and the formation of the solid electrolyte interphase (SEI) layer were observed within the first three cycles. To analyze aging behavior, electrochemical impedance spectroscopy (EIS) was employed to compare changes in electrochemical properties after multiple cycles with and without the application of a magnetic field (300 mT). The results show that the presence of a magnetic field increases both the SEI layer resistance and the charge transfer resistance, reduces the ideality of capacitive behavior, and suppresses sodium-ion diffusion rates. These findings suggest that magnetic fields may adversely affect ion transport and interfacial reactions in sodium-ion batteries. However, for lithium-ion systems, the magnetic field may, under certain conditions, enhance ion diffusion efficiency.

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