School of Materials Science & Engineering, Shaanxi University of Science and Technology, Xi'an Shaanxi 710021, P.R. China.
Nanoscale. 2018 Nov 29;10(46):21671-21680. doi: 10.1039/c8nr06458j.
Surface structure plays a decisive role in the surface capacity and electrochemical kinetics of rechargeable batteries. Tuning the surface structure of building blocks has been considered to be a new effective strategy to promote the electrochemical performance of 3D self-assembled nanoarchitectures. Herein, VS4 microspheres assembled from the nano-units with different crystallinities are synthesized via a facile template-free hydrothermal method. The results show that the electrochemical performance of VS4 microspheres as anode materials for sodium-ion batteries (SIBs) largely depends on their crystallinity, and a VS4 electrode with the lowest crystallinity delivers a high reversible capacity of 412 mA h g-1 at 0.2 A g-1 after 230 cycles and that of 345 and 293 mA h g-1 even at 1.0 and 2.0 A g-1, respectively. The insertion mechanism is revealed within the selected voltage window of 0.50-3.00 V. Further analysis suggests that decreasing the crystallinity of the nano-units can dramatically enhance the pseudocapacitive behavior of VS4 microspheres, which takes the main responsibility for the improvement of sodium storage properties. This work can provide a new insight for the exploration and design of high-performance anodes for SIBs.
表面结构在可充电电池的表面容量和电化学动力学中起着决定性的作用。调整构建块的表面结构被认为是提高 3D 自组装纳米结构电化学性能的一种新的有效策略。本文通过一种简便的无模板水热法合成了由不同结晶度的纳米单元组装而成的 VS4 微球。结果表明，VS4 微球作为钠离子电池（SIBs）阳极材料的电化学性能在很大程度上取决于其结晶度，结晶度最低的 VS4 电极在 0.2 A g-1 下经过 230 次循环后具有 412 mA h g-1 的高可逆容量，在 1.0 和 2.0 A g-1 下的可逆容量分别为 345 和 293 mA h g-1。在 0.50-3.00 V 的选定电压窗口内揭示了插入机制。进一步的分析表明，降低纳米单元的结晶度可以显著提高 VS4 微球的赝电容行为，这是提高钠存储性能的主要原因。这项工作为探索和设计高性能 SIBs 阳极提供了新的思路。
