纳米Co-Sn合金负极材料的制备和电化学性能

Preparation and Electrochemical Properties of Nano-sized Co-Sn Alloy Anode for Lithium Ion Batteries

用水热法于150oC合成了CoSn2纳米合金负极材料。水热反应前还原剂NaBH4的加入速度和水热反应后的热处理均会影响产物的相组成和CoSn2合金组分的颗粒大小,从而影响电极的电化学性能。较大的CoSn2合金颗粒有利于降低电极的首次不可逆容量损失和提高循环稳定性。电极的循环性能还与循环电流密度有关,较小的初始电流密度能够充分激活活性颗粒的嵌锂通道,并在颗粒表面形成较好的固体电解质膜(SEI膜),有利于改善电极的循环性能。

Nano-sized CoSn2 alloy anode materials were synthesized at 150 ℃ through hydrothermal route. The addition rate of the reductant NaBH4 before hydrothermal reaction and the post-annealing process can affect the product compositions and the particle sizes of CoSn2 alloy composite and consequently affect the electrochemical properties of the electrodes. The relatively big particles of CoSn2 alloy are in favor of decreasing the first irreversible capacity loss and enhancing the cycling stability of the electrodes. The electrode cycle performances are also related to the current density. The mild initial charge/discharge current density can fully activate the lithiation routes of the active particles and form a more compact SEI layer on the particle surface, and accordingly improve the electrode cycle performances.