采用简单的反向溶剂法制备出了直径为100 nm左右的高纯、高结晶度的纳米纤维状硒,采用X射线粉末衍射仪、扫描电子显微镜对纤维硒进行结构和形貌的表征。硒纤维电极由于减小了单质硒的尺寸,因而减缓不导电放电产物Li2Se在活性物质Se表面附着所引起的“钝化”作用,从而大大提高了活性物质利用率,减缓了普通硒电极的容量衰减。与普通硒正极相比,硒纤维正极具有更高的比容量和循环稳定性,0.1C(1C=675 mAh/g)倍率下首周放电比容量达到465 mAh/g,40周后容量保持在213 mAh/g。同时由于缩短了锂离子的扩散路径,硒纤维电极比普通硒电极具有更高的电化学活性,其倍率性能得到了大幅提高。
Nano-fibrous selenium of high purity and crystallinity with a diameter of 100 nm were synthesized by the reverse solvent method. The structure and morphology of products were characterized by X-ray diffraction and scan-ning electron microscope, respectively. Since the size of elemental selenium is reduced, the inactivaton effect induced by the coverage of fully insulated discharge product Li2Se on Se particles surface is mitigated, thus greatly improving the utilization coefficient of active materials and alleviating the capacity fading of lithium-selenium batteries. Com-pared with the pristine selenium cathode, Se fiber electrode presents higher specific capacity and better cycling stabil-ity which delivers an initial specific discharge capacity of 465 mAh/g at 0.1C (1C=675 mAh/g) and maintains a capac-ity of 213 mAh/g after 40 cycles. Meanwhile, Se fiber electrode shows higher electrochemical activity than pristine Se electrode due to its shorter lithium ion diffusion path, resulting in a substantially enhanced rate capability of Se fiber electrode.
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