非晶态Fe-P合金电极的电沉积制备及其储锂性能

Electrodeposition and Lithium Storage Performance of Amorphous Fe-P Alloy Electrodes

应用电沉积技术制备了Fe-P合金电极材料。采用X射线衍射(XRD)和扫描电子显微镜(SEM)分析了该合金材料的相结构和表面形貌。XRD分析结果表明电沉积的Fe-P合金具有非晶态结构。电化学性能测试表明:平面结构的Fe-P合金电极首次放电(脱锂)容量达542mAh.g-1,首次循环的库仑效率为60%;50周循环之后放电容量为366mAh.g-1。用非原位的XRD和SEM对电极的充放电机理进行了初步研究,结果表明,首次充电(嵌锂)过程中形成Li3P相,电极表面生成纳米棒结构铁-磷合金,它能有效缓解锂嵌入/脱出时引起的合金结构变化,抑制合金材料的体积膨胀,从而提高该合金电极的充放电效率和循环性能。

The planar structural Fe-P alloy deposits were prepared by electroplating. The structure and electrochemical performance of the electroplated Fe-P alloys have been investigated in detail. XRD results showed that Fe-P alloy deposit exhibits an amorphous state. Electrochemical tests showed that the Fe-P alloy composite electrodes can deliver a discharge capacity of 542 mAh.g^-1 in the first cycle and the coulombic efficiency of 60%. At the 50^th cycle the discharge capacity was 366 mAh.g^-1. The Fe-P electrodes with nanorods structure obtained during cycling was beneficial in reducing the irreversible capacity of Fe-P alloy electrode at initial charge-discharge, and in relaxing the volume expansion during cycling, which improved the cycleability of Fe-P alloy electrode. They are also beneficial to diffusion of Li inset/out of materials, and improve coulombic efficiency in charge-discharge cycle.