Amorphous, Crystalline and Crystalline/Amorphous Selenium Nanowires and Their Different (De)Lithiation Mechanisms

Abstract

Selenium is applied as the cathode material of lithium/selenium (Li–Se) battery, which has high theoretical volumetric capacity density (3253 mA h·cm–3) and high output voltages. However, it has a low melting point (494 K) and a large sensitivity to thermal treatment, which often result in the phase transition between crystalline Se (trigonal phase) and amorphous Se during the charge/discharge cycles of Li–Se battery as reported in literatures. In order to clarify the different chemical (de)lithiation mechanisms between them in Li–Se battery, in this work large-area amorphous selenium (a-Se) nanowires (NWs) have been successfully prepared first through a facile high-energy ball-milling method. Subsequently the crystalline (c) and crystalline/amorphous (c/a) selenium NWs have also been prepared through annealing the above as-obtained amorphous products, respectively. The affirmative composition and morphology of the as-obtained Se nanostructures have been demonstrated by the XRD, SEM, TEM, HRTEM and Raman ...