Layered vanadium-based materials have been extensively studied as promising cathode materials for aqueous zinc-ion batteries (AZIBs). However, challenges remain to achieve the desired high energy conversion efficiency and energy densities as well as long cycling stability requiring an in-depth understanding of the local and the electronic structure of a vanadium-based cathode, especially concerning the impacts on electrochemical potential and mass transfer in the electrochemical process. In this work, 1-butyl-1-methylpyrrolidinium cations are preintercalated into the layered hydrate vanadium pentoxide (V₂O₅·nH₂O) and partially replace the electroneutral structural water, changing the local atomic environment. X-ray absorption spectroscopies demonstrate the V–O bond elongation and the distortion in the [VO₆] octahedra, which alter the ligand field and brings the V 3d state to a lower energy level, ultimately leading to an increase in the electrochemical potential. It is also revealed that the preintercalated organic cations exert electrostatic interaction with lattice oxygen, stabilizing the layered structure and buffering lattice strain during cycling. Consequently, the modified cathode achieves a superior specific capacity of 412 mAh/g at 0.5 A/g and a capacity retention of 97% after 3000 cycles at 8 A/g. The unveiled correlation between local structure and electrochemical performance paves the way for optimizing the cathode materials by manipulating the local coordination environment.

中文翻译：

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揭示有机阳离子预插层钒酸盐正极在水系锌离子电池中的局部结构和配体场


层状钒基材料作为水性锌离子电池 （AZIB） 的有前途的正极材料已被广泛研究。然而，要实现所需的高能量转换效率和能量密度以及长循环稳定性，仍然存在挑战，需要深入了解钒基阴极的局部和电子结构，特别是关于电化学过程中对电化学电位和传质的影响。在本研究中，1-丁基-1-甲基吡咯烷阳离子被预嵌入到层状水合物五氧化二钒 （V₂O₅·nH₂O） 并部分取代电中性结构水，改变局部原子环境。X 射线吸收光谱证明了 V-O 键的伸长和 [VO₆] 八面体的变形，它们改变了配体场并使 V 3d 状态达到较低的能级，最终导致电化学电位增加。研究还揭示了预插层有机阳离子与晶格氧发生静电相互作用，在循环过程中稳定了层状结构并缓冲了晶格应变。因此，改性阴极在 0.5 A/g 下实现了 412 mAh/g 的优异比容量，在 8 A/g 下循环 3000 次后，容量保持率为 97%。揭示局部结构和电化学性能之间的相关性为通过操纵局部配位环境优化正极材料铺平了道路。