The high-pressure form of vanadium pentoxide, β-VO, possesses promising sodium storage properties, featuring reversible sodium intercalation of one Na per formula unit, yielding an appealing capacity of 147 mAh g. However, its short cycle life in conventional carbonate-based electrolytes remains a significant drawback. In this work, we demonstrate that using non-carbonate-based electrolytes markedly enhances key electrochemical performances. Additionally, reducing the particle size of β-VO through milling significantly increases the specific capacity, particularly at high current rates. Milled VO maintains a respectable capacity of 73 mAh g at 1 C rate, compared to the negligible capacity observed in non-milled VO. The milling process also alters the energy storage mechanism. Interestingly, after milling, sodium diffusion coefficient ( increased from 1.78 × 10 to 1.73 × 10 cm s, likely due to induced near-surface defects. Sodium storage exhibits dominant faradaic behavior at slow current rates, while, at high current rates, capacitive processes predominate. The synergy of improved sodium diffusion and additional capacitive charge storage leads to significantly improved electrochemical performance at high current rates. Furthermore, ionic liquid-based electrolytes promote long-life cycling, advancing this material toward practical application as a cathode in sodium-ion cells.

中文翻译：

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提高电化学钠存储性能并深入了解高压多晶型 β-V2O5 中的钠离子扩散


高压形式的五氧化二钒 (β-VO) 具有良好的钠存储性能，具有每个配方单元可逆插入 1 个 Na 的钠，产生 147 mAh g 的诱人容量。然而，其在传统碳酸酯基电解质中的短循环寿命仍然是一个显着的缺点。在这项工作中，我们证明使用非碳酸盐电解质可显着增强关键的电化学性能。此外，通过研磨减小 β-VO 的粒径可显着提高比容量，特别是在高电流速率下。与未研磨的 VO 中观察到的可忽略的容量相比，研磨的 VO 在 1C 倍率下保持了 73 mAh g 的可观容量。铣削过程还改变了能量存储机制。有趣的是，研磨后，钠扩散系数（从 1.78 × 10 cm s 增加到 1.73 × 10 cm s ，可能是由于诱导的近表面缺陷所致。钠存储在低电流速率下表现出占主导地位的法拉第行为，而在高电流速率下，电容过程改进的钠扩散和额外的电容性电荷存储的协同作用可显着提高高电流速率下的电化学性能，此外，基于离子液体的电解质可促进长寿命循环，从而推动该材料作为钠离子阴极的实际应用。细胞。