去合金化制备具有高循环稳定性的纳米多孔Sb/MCNT储钠负极材料

Sodium Storage Behavior of Nanoporous Sb/MCNT Anode Material with High Cycle Stability by Dealloying Route

为提升Sb基负极材料的储钠循环性能,通过简单的两步法(机械辅助化学合金化和酸溶解去合金化)制备纳米化和多孔化的去合金锑/多壁碳纳米管(De-Sb/MCNT)复合物,采用不同方法表征材料的物理化学性质和储钠电化学性能。结果显示,De-Sb/MCNT材料的可逆比容量达到408.6 mAh·g^(-1)(200 mA·g^(-1)),首周库仑效率为69.2%;在800 mA·g^(-1)循环330周后,容量保持率仍可达88%,展现出优异的储钠循环性能。这得益于机械辅助化学合金化/酸溶解去合金化对商品化Sb的“预粉化”作用,促进了材料的纳米化和多孔化,缓解了充放电过程中的体积膨胀,实现了高的循环稳定性。这种常温合金化/去合金化的方法为制备循环稳定的储钠合金负极材料提供了新的途径。

To improve the cycle performance of Sb-based anode materials for sodium storage,a simple two-step method(mechanical assisted chemical alloying and acid dissolution dealloying)is proposed to prepare nano sized and porous antimony/multi-walled carbon nanotube(De-Sb/MCNT)composite.Different methods were employed to characterize the physicochemical and electrochemical properties of De-Sb/MCNT material as anode for sodium storage.The results show that compared to the Raw-Sb/MCNT obtained by direct ball milling of commercial raw Sb and MCNT,the De-Sb/MCNT material exhibits better cycle performance of sodium storage.At a current density of 200 mA·g^(-1),the De-Sb/MCNT delivers the reversible specific capacity of 408.6 mAh·g^(-1) with the initial Coulombic efficiency of 69.2%.After 330 cycles at 800 mA·g^(-1),the capacity retention rate can still retain 88%.The superior cycle performance of De-Sb/MCNT benefits from the“pre-pulverization”effect of mechanically-assisted chemical alloying/acid dissolution dealloying on commercial Sb,which promotes the nanocrystallization and porosity of the material.The De-Sb/MCNT relieves the volume expansion during charging and discharging,thus achieving excellent cycle stability.This dealloying process at ambient temperature is expected to provide a new approach for sodium storage of alloy anode materials with prolonged and stable cycles.