Liu Liang, Zhang Yichi, Wang Yun, Wang Limei, Liu Jian
Automotive Engineering Research Institute, Jiangsu University, Zhenjiang 212013, China.
Jiangsu Autoparts New Energy Technology Co., Ltd., Zhenjiang 212132, China.
ACS Omega. 2024 Jul 27;9(31):33815-33825. doi: 10.1021/acsomega.4c03401. eCollection 2024 Aug 6.
VO has been extensively researched as a battery electrode material due to its ample reserves and high theoretical capacity. However, the synthesis of valence-sensitive VO presents technical challenges as it requires a strict combination of high-temperature treatment and a narrow range of oxygen partial pressures. This study proposes a gentle Li vapor-assisted thermal reduction method to synthesize pure-phase VO at a relatively low temperature of 480 °C without any hazardous gases. It has been discovered that reducing the temperature also improves the specific surface area of the nanoto-mesoscale hierarchical structures and enhances the reactive sites between their secondary grains. These advantages enable the VO micronano particles to store higher levels of Li, Na, and K, increase ionic transport, and tolerate volume expansion. It demonstrates a significant capacity of 767 mA h g in lithium-ion batteries, 393 mA h g in sodium-ion batteries, and 209 mA h g in potassium-ion batteries. It has also been discovered that the crystal structure of VO is easily adjustable by varying the synthesis temperature, which significantly affects the electrochemical storage mechanism. The VO synthesized at 480 °C with low crystallinity exhibits a notable intercalation reaction, facilitating the electrochemical kinetics of reversible insertion/extraction of Li, Na, and K. In contrast, the highly crystalline sample synthesized at 580 °C displays pseudocapacitance behavior instead of an intercalation reaction. The highly crystalline sample synthesized at 680 °C exhibits a thorough pseudocapacitance reaction possessing the capacitive functionality for the electrochemical storage of Na or K with larger ion radii. This study describes a new synthesis strategy and rational modification of vanadium-based electrodes for alkali metal ion batteries, leading to the development of reasonably priced rechargeable battery systems with applications extending beyond lithium-ion batteries.
由于钒氧化物（VO）储量丰富且理论容量高，它作为电池电极材料已得到广泛研究。然而，合成对价态敏感的VO存在技术挑战，因为这需要高温处理和狭窄的氧分压范围严格结合。本研究提出一种温和的锂蒸汽辅助热还原法，在480℃的相对低温下合成纯相VO，且不产生任何有害气体。研究发现，降低温度还能提高纳米至中尺度分级结构的比表面积，并增加其二次颗粒之间的反应位点。这些优点使VO微米纳米颗粒能够存储更高水平的锂、钠和钾，增加离子传输，并耐受体积膨胀。它在锂离子电池中表现出767 mA h g的显著容量，在钠离子电池中为393 mA h g，在钾离子电池中为209 mA h g。还发现通过改变合成温度，VO的晶体结构易于调节，这对电化学存储机制有显著影响。在480℃合成的低结晶度VO表现出明显的嵌入反应，促进了锂、钠和钾可逆插入/脱出的电化学动力学。相比之下，在580℃合成的高结晶度样品表现出赝电容行为而非嵌入反应。在680℃合成的高结晶度样品表现出彻底的赝电容反应，对半径较大的钠或钾离子具有电化学存储的电容功能。本研究描述了一种用于碱金属离子电池的钒基电极的新合成策略和合理改性方法，从而开发出价格合理的可充电电池系统，其应用范围超出锂离子电池。
