Fabrication of core/shell ZnWO4/carbon nanorods and their Li electroactivity

Carbon-coated ZnWO₄ [C-ZW] nanorods with a one-dimensional core/shell structure were synthesised using hydrothermally prepared ZnWO₄ and malic acid as precursors. The effects of the carbon coating on the ZnWO₄ nanorods are investigated by thermogravimetry, high-resolution transmission electron microscopy, and Raman spectroscopy. The coating layer was found to be in uniform thickness of approximately 3 nm. Moreover, the D and G bands of carbon were clearly observed at around 1,350 and 1,600 cm^-1, respectively, in the Raman spectra of the C-ZW nanorods. Furthermore, lithium electroactivities of the C-ZW nanorods were evaluated using cyclic voltammetry and galvanostatic cycling. In particular, the formed C-ZW nanorods exhibited excellent electrochemical performances, with rate capabilities better than those of bare ZnWO₄ nanorods at different current rates, as well as a coulombic efficiency exceeding 98%. The specific capacity of the C-ZW nanorods maintained itself at approximately 170 mAh g^-1, even at a high current rate of 3 C, which is much higher than pure ZnWO₄ nanorods.